Question

In $\Delta ABC$, $\angle B={105}^{\circ }$, $\angle C={50}^{\circ }$. Find $\angle A$. [1 MARK]

Answer 1

Concept: 0.5 Mark
Application: 0.5 Mark

We have,

$\Rightarrow$ $\angle A+\angle B+\angle C={180}^{\circ }$

$\Rightarrow$ $\angle A+{105}^{\circ }+{50}^{\circ }={180}^{\circ }$

$\Rightarrow$ $\angle A={180}^{\circ }-{155}^{\circ }={25}^{\circ }$