Question

Calculate the unknown marked angles in each figure.

Answer 1

Step: Calculate the unknown angle

$a^{\circ }$+${90}^{\circ }$+${40}^{\circ }$ = ${180}^{\circ }$ [∵ Angle sum property of triangle]

⇒ $a^{\circ }$+${130}^{\circ }$ = ${180}^{\circ }$

⇒ $a^{\circ }$ = ${180}^{\circ }$-${130}^{\circ }$

⇒ $a^{\circ }$ = ${50}^{\circ }$

Hence, the unknown angle a is ${50}^{\circ }$.