Question

if ∠abc and ∠def are complementary, and m∠abc is equal to 20°, then what is m∠def? m∠def = ?°

Explanation:

Step1: Recall the definition of complementary angles

Complementary angles sum to \(90^{\circ}\). So, \(m\angle ABC + m\angle DEF=90^{\circ}\).

Step2: Substitute the given value of \(m\angle ABC\)

Given \(m\angle ABC = 20^{\circ}\), substitute into the equation: \(20^{\circ}+m\angle DEF = 90^{\circ}\).

Step3: Solve for \(m\angle DEF\)

Subtract \(20^{\circ}\) from both sides: \(m\angle DEF=90^{\circ}- 20^{\circ}\).

$$m\angle DEF = 70^{\circ}$$

Answer:

\(70\)