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Classify an angle of 90

Step by step, with the reason for every step · Classifying angles and triangles · Geometry

Step by step

The question

Question: find what kind of angle 90° is.

1 Compare with 90° and 180°

There are five kinds of angles.

Each name says how big the angle is, next to 90° and 180°.

90 is exactly 90.

90 = 90

Careful!

Look at the size next to 90° and 180°.

Careful: right: exactly a square corner

2 Name it

So 90° is right.

90° is right

3 Check

Let's check with the picture.

The dashed line up makes a square corner: 90°.

The dashed line to the left makes a straight line: 180°.

Our angle fits the square corner exactly.

So it is a right angle.

Let's look back.

First: compare with 90° and 180°.

Then: name it.

Last: check.

Answer
90° is right

Your turn

Try this one yourself, then check:

What kind of angle?
Show the answer
acute

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