Question

The sum of two angles of a triangle is ${80}^{\circ }$ and their difference is ${20}^{\circ }$. Find all the angles. [4 MARKS]

Answer 1

Concept : 1 Mark
Process : 2 Marks
Result : 1 Mark

Let ABC be the triangle

Given that,

$\angle$A + $\angle$B = ${80}^{\circ }$ and $\angle$A - $\angle$B =${20}^{\circ }$

Adding the two equations, we get

$\angle$A = ${50}^{\circ }$ and $\angle$B = ${30}^{\circ }$

We know that,

$\angle$A + $\angle$B + $\angle$C = ${180}^{\circ }$ [Angle sum property]

$\Rightarrow \angle$C = ${100}^{\circ }$