Page 148 - New Medley 5 Semester 2

Thus, ∠LMP and ∠NMP form a pair of supplementary angles. In other
words, if the sum of two angles is 180°, then the angles are said to be

supplementary angles.

  To find the complement of an angle, we subtract its measure from 90°.

  To find the supplement of an angle, we subtract its measure from 180°.

Example 2: Find the complementary angles of the given angles.

(a) 45° (b) 10° (c) 0° (d) 75°

Solution: We know that the sum of two complementary angles is

90°. Therefore,

(a) Complement of 45° = 90° – 45° = 45°

(b) Complement of 10° = 90° – 10° = 80°

(c) Complement of 0° = 90° – 0° = 90°

(d) Complement of 75° = 90° – 75° = 15°

Example 3: Find the supplementary angle of each of the following.

(a) 45° (b) 130° (c) 90° (d) 180°

Solution: We know that if the sum of two angles is 180°, the two

angles are supplementary to each other. Therefore,

(a) Supplement of 35° = 180° – 45° = 135°

(b) Supplement of 130° = 180° – 130° = 50°

(c) Supplement of 90° = 180° – 90° = 90°

(d) Supplement of 180° = 180° – 180° = 0°

Construction of an Angle with Protractor

We have learnt the use of a protractor for measuring angles. We can also
use it to construct an angle of the given measurement.

Constructing an Angle of Measure 40°

To construct an angle of 40°, follow these steps:

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