IDENTIFYING THE TYPES OF ANGLES

Obtuse angle :

The angle measure which is greater than 90 degree and lesser than 180 degree is called obtuse angle.

Acute angle :

The angle measure which is lesser than 90 degree is called acute angle.

Right angle :

90 degree angle measure is known as right angle.

Identify the following angles as acute, obtuse or right angles :

Problem 1 :

124^º

Solution :

An angle that is greater than 90^º and less than 180^º is called obtuse angle.

Problem 2 :

109^º

Solution :

An angle that is greater than 90^º and less than 180^º is called obtuse angle.

Problem 3 :

46^º

Solution :

An angle that is greater than 0^º and less than 90^º is called acute angle.

Problem 4 :

97^º

Solution :

An angle that is greater than 90^º and less than 180^º is called obtuse angle.

Problem 5 :

90^º

Solution :

An angle that is exactly 90^º is called right angle.

Problem 6 :

72^º

Solution :

An angle that is greater than 0^º and less than 90^º is called acute angle.

Problem 7 :

163^º

Solution :

An angle that is greater than 90^º and less than 180^º is called obtuse angle.

Problem 8 :

84^º

Solution :

An angle that is greater than 0^º and less than 90^º is called acute angle.

Problem 9 :

134^º

Solution :

An angle that is greater than 90^º and less than 180^º is called obtuse angle.

Problem 10 :

23^º

Solution :

An angle that is greater than 0^º and less than 90^º is called acute angle.

Problem 11 :

166^º

Solution :

An angle that is greater than 90^º and less than 180^º is called obtuse angle.

Problem 12 :

35^º

Solution :

An angle that is greater than 0^º and less than 90^º is called acute angle.

Problem 13 :

Here are two angles.

a) What type of angle is angle X?

b) What type of angle is angle Y?

c) Which angle is smaller?

How do you know?

Solution :

a) Angle X, it is greater than 90 degree. So, it is obtuse angle.

b) Angle Y, it is lesser than 90 degree. So, it is acute angle.

c) Angle Y is smaller.

Always acute angle is smaller than obtuse angle.

Problem 14 :

Order the angles from greatest to smallest.

Solution :

Comparing angles a and d, d is the greater angle.

Comparing b and c, b is the right angle and c is the acute angle.

Angles from greatest to least d, a, c and b.