Question

Two of the exterior angles of a triangle are $158^\circ$ and $99^\circ.$ Find the third exterior angle, in degrees.

Answer 1

Answer:

The third exterior angle is $103^o$

Step-by-step explanation:

Given

$\theta = 158^o$

$\alpha = 99^o$

Required

The third exterior angle $(\beta)$

The exterior angles of a triangle add up to 360 degrees.

So:

$\theta + \alpha + \beta = 360^o$

Make $\beta$ the subject

$\beta = 360^o - (\theta + \alpha)$

Substitute known values

$\beta = 360^o - (158^o + 99^o)$

$\beta = 103^o$