Complementary Angles – Rules With Example
Concept
Understanding complementary angles.
Rules
How to find complement of an angle?
1. Complementary angles are two angles whose sum is 90 degrees.
2. Subtract the given angle from 90° to find the complementary angle.
Example
Find the measure of x in the figure.
Solution
The angles are complementary. Complementary angles are two angles whose sum is 90 degrees.
Therefore,
x + 48° = 90°
Subtract 48° from both sides of the equation
x + 48° – 48° = 90° – 48°
x = 42°
Practice Complementary Angles
Practice Problem 1
Find the measure of x in the figure.
Practice Problem 2
The measure of angle A is 26°, find the measure of its complementary angle.
Practice Problem 3
Find the measure of x in the figure.
Practice Problem 4
Find the value of unknown variable.
Vertex – is the point where two rays of an angle meet.
Angle – a figure formed by two rays, sharing a common endpoint, called the vertex of the angle.
Complementary angles – two angles whose sum is 90 degrees.
Supplementary angles – two angles whose sum is 180 degrees.
Pre-requisite Skills
Measuring Angles
Classifying Angles
Related Skills
Estimating Angles
Angles
Finding Angle Measures