Triangle Basics worksheet with questions on classifying triangles by sides and angles, and solving for 'x'.

Let’s solve each part of the worksheet step by step.

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## Part 1: Classify each triangle by the length of its SIDES

1. Triangle with all angles 60° and all sides marked with single tick marks

- All three sides are equal (indicated by identical tick marks).
- Classification: Equilateral triangle

> ✔ Answer: Equilateral

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2. Triangle with a right angle and two sides marked with single tick marks

- Two sides are equal (tick marks), and one angle is 90°.
- This is an isosceles right triangle — but since we’re classifying by *side lengths*, it’s isosceles.
- (Note: “Isosceles” means at least two sides equal — which is true here.)

> ✔ Answer: Isosceles

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3. Triangle with angles 45°, 70°, 65° and all three sides marked differently (single, double, triple tick marks)

- All three sides have different markings → all sides are unequal.
- Classification: Scalene triangle

> ✔ Answer: Scalene

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## Part 2: Classify each triangle by its ANGLES

4. Triangle with angles 45°, 70°, 65°

- All angles are less than 90° → acute triangle
- (Even though side lengths vary, we’re classifying by angles.)

> ✔ Answer: Acute

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5. Triangle with all angles 60°

- All angles < 90° → still acute
- Also equiangular, but classification by angles is acute

> ✔ Answer: Acute

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6. Triangle with a right angle (square symbol) and two sides equal (tick marks)

- Has one 90° angle → right triangle
- (We ignore side equality for angle classification — just look at angles.)

> ✔ Answer: Right

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## Part 3: Find the value of ‘x’ in each of the following

7. Triangle with angles x°, 52°, and 35°

- The sum of interior angles in any triangle is always 180°.
- So:

> x + 52 + 35 = 180

> x + 87 = 180

> x = 180 - 87 = 93

> ✔ Answer: 93

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## ✔ Final Answers:

1. Equilateral
2. Isosceles
3. Scalene
4. Acute
5. Acute
6. Right
7. 93

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