Question

triangle abc, shown in the diagram below, is an isosceles triangle where $overline{ab}congoverline{ac}$. what is the measure, in degrees, of $angle cab? 89^{circ} 43^{circ} 50^{circ} 115^{circ}$

Explanation:

Step1: Find $\angle ACB$

$\angle ACB = 180^{\circ}- 115^{\circ}=65^{\circ}$

Step2: Use isosceles - triangle property

Since $\overline{AB}\cong\overline{AC}$, $\angle ABC=\angle ACB = 65^{\circ}$

Step3: Calculate $\angle CAB$

$\angle CAB=180^{\circ}-2\times65^{\circ}=180^{\circ}-130^{\circ}=50^{\circ}$

Answer:

C. $50^{\circ}$