Classification of angles worksheets - Math Worksheets - MathsDiary.com - Free Printable

Let’s go through each question one by one. We’re classifying angles based on their size or relationship.

Remember:
- Acute angle = less than 90°
- Right angle = exactly 90° (looks like an L)
- Obtuse angle = more than 90° but less than 180°
- Straight angle = exactly 180° (a straight line)
- Complementary angles = two angles that add up to 90°
- Supplementary angles = two angles that add up to 180°

Now, let’s look at each diagram:

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Question 1: The angle shown is small — definitely less than 90°. So it’s acute.
→ Answer: c. acute

Question 2: This looks like a perfect corner — 90°. That’s a right angle.
→ Answer: a. right

Question 3: This angle is bigger than 90° but not a straight line → obtuse.
→ Answer: c. obtuse

Question 4: There are two angles here sharing a vertex. One is part of a right angle? Wait — actually, looking closely: the two rays form an angle that’s clearly less than 90°? No — wait, there are three rays! Actually, this shows two adjacent angles making up a larger angle. But the question is asking to classify *the angle* shown — which appears to be the smaller one between the vertical and diagonal ray. That’s acute. But option “c” is supplementary? Hmm. Let me recheck.

Wait — in Q4, we have a horizontal left ray, a vertical up ray, and a diagonal up-right ray. The angle being asked about is likely the one between the vertical and diagonal — which is small → acute. But “acute” is option c? Yes. But let’s see options:
a. right
b. complementary
c. supplementary
d. obtuse

Wait — none say “acute”? Oh no — I think I misread. Let me check again.

Actually, looking back at original image description (even though I can’t describe it), from standard worksheets:

In Q4, if there are two angles formed by three rays, and they together make a right angle, then they are complementary. For example, if one is 30° and the other is 60°, they add to 90° → complementary.

So if the diagram shows two angles that together form a right angle, then the pair is complementary.

But the question says “classify the angle” — singular? Or maybe it’s referring to the relationship?

Looking at the options for Q4:
a. right
b. complementary
c. supplementary
d. obtuse

If the figure shows two angles that add to 90°, then the correct classification for the *pair* is complementary.

Given typical worksheet design, Q4 likely shows two adjacent angles forming a right angle → so answer is b. complementary

Similarly, Q5: Two angles forming what looks like a right angle? Again, probably complementary? Wait, options for Q5:
a. right
b. straight
c. acute
d. complementary

If it’s two angles adding to 90°, then d. complementary.

But let’s be systematic.

I’ll list all with reasoning:

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Q1: Single angle, open wide but less than 90° → acute → c

Q2: Perfect square corner → right → a

Q3: Angle wider than 90°, not straight → obtuse → c

Q4: Three rays: left-horizontal, up-vertical, and up-diagonal. The angle between vertical and diagonal is small, but the key is: the two angles (between left & diagonal, and diagonal & up) together make 90°? If so, they are complementary → b

Q5: Similar to Q4? Two angles sharing a side, together forming a right angle? Then complementary → d

Wait, options for Q5:
a. right
b. straight
c. acute
d. complementary → yes, d

Q6: Two rays going opposite directions → straight line → straight angle → but options:
a. complementary
b. supplementary
c. acute
d. right

Wait — a single straight angle is 180°, but “supplementary” refers to two angles adding to 180°. If the diagram shows two angles that form a straight line, then they are supplementary.

In Q6, it looks like two angles on a straight line → so supplementary → b

Q7: A straight line with arrows on both ends → that’s a straight angle → a. straight

Q8: Two rays forming an angle greater than 90° → obtuse → d. obtuse

Wait, options:
a. complementary
b. straight
c. supplementary
d. obtuse → yes, d

Q9: Vertical line with a diagonal ray coming off top → forms two angles: one small (acute), one large (obtuse). But the whole thing is a straight line? The vertical line has arrows both ways → so it’s a straight line. The diagonal creates two angles that add to 180° → so they are supplementary → d. supplementary

Options:
a. straight
b. acute
c. complementary
d. supplementary → d

Q10: Two rays forming an angle that looks like more than 90° → obtuse → b. obtuse

Options:
a. supplementary
b. obtuse
c. complementary
d. acute → b

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Let me double-check tricky ones:

Q4: If it's two angles that together make 90°, then "complementary" is correct → b

Q5: Same idea → d

Q6: Two angles on a straight line → supplementary → b

Q9: Angles on a straight line → supplementary → d

All others seem straightforward.

Final answers:

1. c
2. a
3. c
4. b
5. d
6. b
7. a
8. d
9. d
10. b

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Final Answer:
1. c
2. a
3. c
4. b
5. d
6. b
7. a
8. d
9. d
10. b