Question

The angles of a pentagon are x°, (x + 20)°. (x + 40)°, (x + 60)° and (x + 80)°. The smallest angle of the pentagon is 

A. 75° 

B. 68° 

C. 78° 

D. 85°

Answer 1

The sum of interior angles of pentagon is 

= (n – 2) × 180° [n is number of sides of polygon)] 

= (5 – 2) x 180° 

= 540° 

x + (x + 20) + (x + 40) + (x + 60) + (x + 80) = 540 

5x + 200 = 540 

5x = 340 

x = 340 / 5 

= 68° 

So, smallest angle of pentagon is 68°