Question

prove that the sum of three angles of a triangle is two right angles. if in a right angled triangle an acute angle is one fourth the other, find the acute angle

Answer 1

x = smaller acute angle in right triangle 
4x = larger acute angle 
90 = right angle 

x + 4x + 90 = 180 
5x = 90 
x = 18 
4x = 72 

Acute angles are 18° and 72°

Answer 2

Answer:

18° and 72°

Step-by-step explanation:

Sum of all sides of a triangle is 180.

Let the smallest angle be x  

Thus the larger acute angle  will be 4x

And the 3rd side is 90.

Thus the following equation is formed.

x + 4x + 90 = 180  

5x = 90  

x = 18  

4x = 72  

Hence the acute angles are:

18° and 72°

Hope it helps :D