Geometry Worksheets | Angles Worksheets - Free Printable

Let’s go step by step to classify each angle.

First, remember the definitions:

- Acute angle: Less than 90°
- Right angle: Exactly 90° (looks like a corner of a square)
- Obtuse angle: More than 90° but less than 180°
- Straight angle: Exactly 180° (looks like a straight line)

Now let’s look at each one:

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Visual Angles (1–10):

We estimate based on how wide the angle opens.

1) Looks wider than 90° → obtuse
2) Very small opening → acute
3) Wider than 90° → obtuse
4) Small opening → acute
5) Almost flat, but not quite — wait, actually it looks like a straight line? Let me check again. The two rays are pointing in opposite directions — that’s a straight line → straight
6) Slightly more than 90° → obtuse
7) Clearly more than 90° → obtuse
8) Very narrow → acute
9) Looks like a right angle? Wait — no, it’s slightly open more than 90°? Actually, looking closely, it might be obtuse. But let’s compare to known shapes. Hmm — actually, this one is tricky. Let’s say it’s obtuse for now.
Wait — better approach: if it’s bigger than an L-shape (90°), it’s obtuse. If smaller, acute. This one is bigger → obtuse
10) Small opening → acute

Actually, let’s double-check #5 and #9.

#5: Two arrows going left and right — definitely a straight line → straight

#9: It’s bent — not 90°, not 180° — looks like about 100° or so → obtuse

Okay, revised:

1) obtuse
2) acute
3) obtuse
4) acute
5) straight
6) obtuse
7) obtuse
8) acute
9) obtuse
10) acute

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Numerical Angles (11–20):

Just compare the number to 90 and 180.

11) 84° → less than 90 → acute
12) 89° → still less than 90 → acute
13) 25° → way less → acute
14) 50° → less → acute
15) 180° → exactly straight → straight
16) 166° → between 90 and 180 → obtuse
17) 90° → exactly right → right
18) 125° → between 90 and 180 → obtuse
19) 149° → same → obtuse
20) 106° → same → obtuse

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Final Answer:

1) obtuse
2) acute
3) obtuse
4) acute
5) straight
6) obtuse
7) obtuse
8) acute
9) obtuse
10) acute
11) acute
12) acute
13) acute
14) acute
15) straight
16) obtuse
17) right
18) obtuse
19) obtuse
20) obtuse