Question

1. ∠3 is the complement of ∠1, and m∠3 = 20°. find m∠1

a) 160°
b) 20°
c) 40°
d) 70°

Explanation:

Step1: Recall complement - angle definition

Complementary angles sum to 90°.

Step2: Set up the equation

Let \(m\angle1=x\). Since \(\angle3\) is the complement of \(\angle1\), \(x + m\angle3=90^{\circ}\).

Step3: Substitute the value of \(m\angle3\)

Given \(m\angle3 = 20^{\circ}\), then \(x+20^{\circ}=90^{\circ}\).

Step4: Solve for \(x\) (which is \(m\angle1\))

\(x=m\angle1=90^{\circ}- 20^{\circ}=70^{\circ}\).

Answer:

D. 70°