Question

Find the value of $\angle C$ in the below triangle if the value of $\angle CAB$ = 25${}^o$. If AB = BD, then what can be the value of $\angle D$ [3 MARKS]

Answer 1

Steps: 1 Mark
Solution for $\angle C$ and $\angle D$: 2 Marks

In the given triangle CAB
Sum of interior angles = exterior angle
Or, $\angle C$ + $\angle CAB$ = 90${}^o$
Or, $\angle C$ = 90${}^o$ - 25${}^o$
Or, $\angle C$ = 65${}^o$

$\because$ AB = BD $\Rightarrow \angle BAD=\angle D=y\left(say\right)$ (Equal sides have equal angles opposite to them.)
$\Rightarrow \angle BAD+\angle D+90=180$ \
$\Rightarrow \angle BAD+\angle D=90$