Question

the pentagon has 3 angles which are each 140°. The other two interior angles are equal. calculate the size of one of these angles​

Answer 1

60°

Explanation:

The sum of the interior angles of a polygon is

sum = 180° (n - 2) ← n is the number of sides

Here n = 5 ( pentagon ), thus

sum = 180° × 3 = 540°

let x be the size of the equal angles

Sum the interior angles and equate to 540

(3 × 140 ) + 2x = 540

420 + 2x = 540 ( subtract 240 from both sides )

2x = 120 ( divide both sides by 2 )

x = 60

Thus the size of 1 of the 2 equal angles = 60°