Math worksheet for calculating the area of compound shapes with various geometric figures and dimensions.
Worksheet titled "Compound Shapes" with nine geometric figures, each labeled with dimensions and a space to calculate the area. The figures include combinations of triangles, rectangles, semicircles, and trapezoids.
PNG
612×792
9.3 KB
Free · Personal Use
Quality Assured by Worksheets Library Team
Reviewed for educational accuracy and age-appropriateness
ID: #537053
⭐
Show Answer Key & Explanations
Step-by-step solution for: Geometry Worksheets | Area and Perimeter Worksheets | Geometry ...
▼
Show Answer Key & Explanations
Step-by-step solution for: Geometry Worksheets | Area and Perimeter Worksheets | Geometry ...
Let’s solve each compound shape one by one. We’ll break them into simpler shapes (like rectangles, triangles, semicircles), find their areas, and add or subtract as needed. Remember:
- Area of rectangle = length × width
- Area of triangle = ½ × base × height
- Area of circle = πr² → so semicircle = ½πr²
Use π ≈ 3.14 if needed.
---
Problem 1: Trapezoid-like shape (actually a right trapezoid)
It has two parallel sides: 14 in and 7 in, with height 14 in (the bottom side).
Area of trapezoid = ½ × (sum of parallel sides) × height
= ½ × (14 + 7) × 14
= ½ × 21 × 14
= 10.5 × 14 = 147.0 in²
✔ Check: Yes, that’s correct.
---
Problem 2: Rectangle + Semicircle on top
Rectangle: 18 cm × 18 cm → area = 324 cm²
Semicircle: diameter = 9 cm → radius = 4.5 cm
Area of semicircle = ½ × π × r² = ½ × 3.14 × (4.5)²
= ½ × 3.14 × 20.25 = 1.57 × 20.25 ≈ 31.7925
Total area = 324 + 31.7925 ≈ 355.8 cm²
✔ Rounded to one decimal: 355.8
---
Problem 3: Rectangle + Semicircle on top
Rectangle: 20 yd × 15 yd = 300 yd²
Semicircle: diameter = 6 yd → radius = 3 yd
Area = ½ × π × 3² = ½ × 3.14 × 9 = 1.57 × 9 = 14.13
Total = 300 + 14.13 = 314.1 yd²
✔ Rounded: 314.1
---
Problem 4: Triangle + Semicircle below
Triangle: base = ? Wait — the diagram shows a triangle with height 12 m, and the base is the same as the diameter of the semicircle? Actually, looking at the figure: it's a triangle sitting on top of a semicircle. The dashed line is 8 m — that’s the radius of the semicircle? No — wait, the label says “8 m” with an arrow pointing to the radius of the semicircle. So radius = 8 m → diameter = 16 m → that’s the base of the triangle too.
So:
- Triangle: base = 16 m, height = 12 m → area = ½ × 16 × 12 = 96 m²
- Semicircle: radius = 8 m → area = ½ × π × 64 = 32π ≈ 32 × 3.14 = 100.48 m²
Total = 96 + 100.48 = 196.5 m²
✔ Rounded: 196.5
Wait — let me double-check the diagram description. It says “12 m” for the triangle height, and “8 m” with an arrow to the radius of the semicircle. Yes, so base of triangle = diameter = 16 m. Correct.
---
Problem 5: T-shaped figure — can be split into two rectangles.
Top rectangle: 12 in wide × 12 in tall → area = 144 in²
Bottom rectangle: 20 in wide × 12 in tall → area = 240 in²
But wait — they overlap? No, actually, the top rectangle sits centered on the bottom one. But since we’re just adding areas, and there’s no overlap in the shaded region, total area = 144 + 240 = 384 in²
✔ Simple addition — yes.
---
Problem 6: Rectangle + Triangle on the right
Left part: rectangle 20 cm × 20 cm = 400 cm²
Right part: triangle with base 10 cm and height 20 cm → area = ½ × 10 × 20 = 100 cm²
Total = 400 + 100 = 500.0 cm²
✔ Easy.
---
Problem 7: Triangle + Semicircle
Triangle: right triangle with legs 13 ft and 6 ft? Wait — the diagram shows a vertical side 13 ft, horizontal side 6 ft, and a right angle between them? Actually, looking: it’s a right triangle with base 6 ft and height 13 ft? But then attached to the base is a semicircle with radius 6 ft? That doesn’t make sense — because the semicircle is drawn under the 6 ft side.
Actually, re-examining: the triangle has height 13 ft, and the base is 6 ft (same as the diameter of the semicircle? Or radius?) — the label says “6 ft” with an arrow to the radius of the semicircle. So radius = 6 ft → diameter = 12 ft. But the triangle’s base is only 6 ft? That doesn’t match.
Wait — perhaps the triangle is attached to the flat side of the semicircle. If the semicircle has radius 6 ft, its diameter is 12 ft. But the triangle’s base is labeled 6 ft? That seems inconsistent.
Looking again: In problem 7, the figure is a right triangle with vertical leg 13 ft, horizontal leg 6 ft, and then a semicircle attached to the horizontal leg — but the semicircle’s radius is labeled 6 ft? That would mean the diameter is 12 ft, but the leg is only 6 ft. That can’t be.
Perhaps the “6 ft” is the radius, and the triangle’s base is also 6 ft? Then the semicircle is drawn with radius 6 ft, meaning it extends beyond the triangle? That might be possible.
Assume:
- Triangle: base = 6 ft, height = 13 ft → area = ½ × 6 × 13 = 39 ft²
- Semicircle: radius = 6 ft → area = ½ × π × 36 = 18π ≈ 18 × 3.14 = 56.52 ft²
Total = 39 + 56.52 = 95.5 ft²
✔ Rounded: 95.5
Even though the geometry looks odd, based on labels, this is what we have.
---
Problem 8: House-shaped figure — rectangle + triangle on top
Rectangle: 6 yd wide × 8 yd tall → area = 48 yd²
Triangle: base = 6 yd, height = 9 yd → area = ½ × 6 × 9 = 27 yd²
Total = 48 + 27 = 75.0 yd²
✔ Straightforward.
---
Problem 9: L-shaped figure — can be split into two rectangles.
Option 1: Left rectangle: 11 ft high × 10 ft wide = 110 ft²
Right rectangle: 8 ft high × 8 ft wide = 64 ft²
But wait — do they overlap? The total width is 10 + 8 = 18 ft, and heights are different. Actually, the left part is 11 ft tall, right part is 8 ft tall, and they share a common side? Better to think:
The whole shape can be seen as a big rectangle minus a missing corner, but easier to split vertically:
- Left rectangle: width 10 ft, height 11 ft → 110 ft²
- Right rectangle: width 8 ft, height 8 ft → 64 ft²
But the right rectangle starts at the bottom, so no overlap. Total = 110 + 64 = 174.0 ft²
Alternatively, split horizontally:
- Bottom rectangle: full width 18 ft × 8 ft = 144 ft²
- Top rectangle: only left part, 10 ft wide × (11-8)=3 ft tall = 30 ft²
Total = 144 + 30 = 174 ft² — same answer.
✔ Confirmed.
---
Now, compiling all answers:
1) 147.0
2) 355.8
3) 314.1
4) 196.5
5) 384.0
6) 500.0
7) 95.5
8) 75.0
9) 174.0
All rounded to one decimal place as instructed.
Final Answer:
1) 147.0 in²
2) 355.8 cm²
3) 314.1 yd²
4) 196.5 m²
5) 384.0 in²
6) 500.0 cm²
7) 95.5 ft²
8) 75.0 yd²
9) 174.0 ft²
- Area of rectangle = length × width
- Area of triangle = ½ × base × height
- Area of circle = πr² → so semicircle = ½πr²
Use π ≈ 3.14 if needed.
---
Problem 1: Trapezoid-like shape (actually a right trapezoid)
It has two parallel sides: 14 in and 7 in, with height 14 in (the bottom side).
Area of trapezoid = ½ × (sum of parallel sides) × height
= ½ × (14 + 7) × 14
= ½ × 21 × 14
= 10.5 × 14 = 147.0 in²
✔ Check: Yes, that’s correct.
---
Problem 2: Rectangle + Semicircle on top
Rectangle: 18 cm × 18 cm → area = 324 cm²
Semicircle: diameter = 9 cm → radius = 4.5 cm
Area of semicircle = ½ × π × r² = ½ × 3.14 × (4.5)²
= ½ × 3.14 × 20.25 = 1.57 × 20.25 ≈ 31.7925
Total area = 324 + 31.7925 ≈ 355.8 cm²
✔ Rounded to one decimal: 355.8
---
Problem 3: Rectangle + Semicircle on top
Rectangle: 20 yd × 15 yd = 300 yd²
Semicircle: diameter = 6 yd → radius = 3 yd
Area = ½ × π × 3² = ½ × 3.14 × 9 = 1.57 × 9 = 14.13
Total = 300 + 14.13 = 314.1 yd²
✔ Rounded: 314.1
---
Problem 4: Triangle + Semicircle below
Triangle: base = ? Wait — the diagram shows a triangle with height 12 m, and the base is the same as the diameter of the semicircle? Actually, looking at the figure: it's a triangle sitting on top of a semicircle. The dashed line is 8 m — that’s the radius of the semicircle? No — wait, the label says “8 m” with an arrow pointing to the radius of the semicircle. So radius = 8 m → diameter = 16 m → that’s the base of the triangle too.
So:
- Triangle: base = 16 m, height = 12 m → area = ½ × 16 × 12 = 96 m²
- Semicircle: radius = 8 m → area = ½ × π × 64 = 32π ≈ 32 × 3.14 = 100.48 m²
Total = 96 + 100.48 = 196.5 m²
✔ Rounded: 196.5
Wait — let me double-check the diagram description. It says “12 m” for the triangle height, and “8 m” with an arrow to the radius of the semicircle. Yes, so base of triangle = diameter = 16 m. Correct.
---
Problem 5: T-shaped figure — can be split into two rectangles.
Top rectangle: 12 in wide × 12 in tall → area = 144 in²
Bottom rectangle: 20 in wide × 12 in tall → area = 240 in²
But wait — they overlap? No, actually, the top rectangle sits centered on the bottom one. But since we’re just adding areas, and there’s no overlap in the shaded region, total area = 144 + 240 = 384 in²
✔ Simple addition — yes.
---
Problem 6: Rectangle + Triangle on the right
Left part: rectangle 20 cm × 20 cm = 400 cm²
Right part: triangle with base 10 cm and height 20 cm → area = ½ × 10 × 20 = 100 cm²
Total = 400 + 100 = 500.0 cm²
✔ Easy.
---
Problem 7: Triangle + Semicircle
Triangle: right triangle with legs 13 ft and 6 ft? Wait — the diagram shows a vertical side 13 ft, horizontal side 6 ft, and a right angle between them? Actually, looking: it’s a right triangle with base 6 ft and height 13 ft? But then attached to the base is a semicircle with radius 6 ft? That doesn’t make sense — because the semicircle is drawn under the 6 ft side.
Actually, re-examining: the triangle has height 13 ft, and the base is 6 ft (same as the diameter of the semicircle? Or radius?) — the label says “6 ft” with an arrow to the radius of the semicircle. So radius = 6 ft → diameter = 12 ft. But the triangle’s base is only 6 ft? That doesn’t match.
Wait — perhaps the triangle is attached to the flat side of the semicircle. If the semicircle has radius 6 ft, its diameter is 12 ft. But the triangle’s base is labeled 6 ft? That seems inconsistent.
Looking again: In problem 7, the figure is a right triangle with vertical leg 13 ft, horizontal leg 6 ft, and then a semicircle attached to the horizontal leg — but the semicircle’s radius is labeled 6 ft? That would mean the diameter is 12 ft, but the leg is only 6 ft. That can’t be.
Perhaps the “6 ft” is the radius, and the triangle’s base is also 6 ft? Then the semicircle is drawn with radius 6 ft, meaning it extends beyond the triangle? That might be possible.
Assume:
- Triangle: base = 6 ft, height = 13 ft → area = ½ × 6 × 13 = 39 ft²
- Semicircle: radius = 6 ft → area = ½ × π × 36 = 18π ≈ 18 × 3.14 = 56.52 ft²
Total = 39 + 56.52 = 95.5 ft²
✔ Rounded: 95.5
Even though the geometry looks odd, based on labels, this is what we have.
---
Problem 8: House-shaped figure — rectangle + triangle on top
Rectangle: 6 yd wide × 8 yd tall → area = 48 yd²
Triangle: base = 6 yd, height = 9 yd → area = ½ × 6 × 9 = 27 yd²
Total = 48 + 27 = 75.0 yd²
✔ Straightforward.
---
Problem 9: L-shaped figure — can be split into two rectangles.
Option 1: Left rectangle: 11 ft high × 10 ft wide = 110 ft²
Right rectangle: 8 ft high × 8 ft wide = 64 ft²
But wait — do they overlap? The total width is 10 + 8 = 18 ft, and heights are different. Actually, the left part is 11 ft tall, right part is 8 ft tall, and they share a common side? Better to think:
The whole shape can be seen as a big rectangle minus a missing corner, but easier to split vertically:
- Left rectangle: width 10 ft, height 11 ft → 110 ft²
- Right rectangle: width 8 ft, height 8 ft → 64 ft²
But the right rectangle starts at the bottom, so no overlap. Total = 110 + 64 = 174.0 ft²
Alternatively, split horizontally:
- Bottom rectangle: full width 18 ft × 8 ft = 144 ft²
- Top rectangle: only left part, 10 ft wide × (11-8)=3 ft tall = 30 ft²
Total = 144 + 30 = 174 ft² — same answer.
✔ Confirmed.
---
Now, compiling all answers:
1) 147.0
2) 355.8
3) 314.1
4) 196.5
5) 384.0
6) 500.0
7) 95.5
8) 75.0
9) 174.0
All rounded to one decimal place as instructed.
Final Answer:
1) 147.0 in²
2) 355.8 cm²
3) 314.1 yd²
4) 196.5 m²
5) 384.0 in²
6) 500.0 cm²
7) 95.5 ft²
8) 75.0 yd²
9) 174.0 ft²
Parent Tip: Review the logic above to help your child master the concept of area of composite figures worksheet 7th grade answers.