Question

A triangle has two angles measuring 69 and 77. Determine the measure of the third angle b

Answer 1

Answer:

$m\angle B=34\°$

Step-by-step explanation:

Given measures of 2 angles of a triangle :

m∠A = 69°

m∠C = 79°

Find m∠B.

We know that sum of angles of a triangle =180°

So, we have

$m\angle A+m\angle B+m\angle C=180\°$

Substituting the vales of m∠A = 69° and m∠C = 79°

$69\°+m\angle B+77\°=180\°$

Adding like terms.

$m\angle B+146\°=180\°$

Subtracting both sides by 146°.

$m\angle B+146\°-146\°=180\°-146\°$

∴ $m\angle B=34\°$ (Answer)