Question

1. choose the best answer.

m∠acd = 120°
m∠acb = 20°
what is the measure of ∠bcd ?
120°
20°
140°
100°

Explanation:

Step1: Identify angle relationship

We know that \( \angle ACD = \angle ACB + \angle BCD \). So, to find \( \angle BCD \), we can use the formula \( \angle BCD=\angle ACD - \angle ACB \).

Step2: Substitute values

Given \( m\angle ACD = 120^{\circ} \) and \( m\angle ACB = 20^{\circ} \), substitute these values into the formula: \( \angle BCD = 120^{\circ}- 20^{\circ} \).

Step3: Calculate the result

\( 120^{\circ}- 20^{\circ}=100^{\circ} \).

Answer:

\( 100^{\circ} \) (corresponding to the option with \( 100^{\circ} \))