Question

the angle A of a triangle ABC is equal to the sum of other two angles.Also ,the ratio of the angle B to the angle C is 4:5. find the measure of each angle

Answer 1

By angle sum property of triangle,
A+B+C=180
(4x+5x)+4x+5x=180
9x+9x=180
18x=180
x=10
A=9x=90
B=4x=40
C=5x=50

Answer 2

Hi ,

According to the problem given,




We know that,

Sum of the three angles in a triangle

Is equals to 180°

A + B + C = 180----( 3 )

A + A = 180 [ from ( 1 ) ]

2A = 180

A = 180 / 2

A = 90 ---- ( 4 )

Put A = 90 in ( 3 ).,

90 + B + C = 180

B+ C = 90

4C/5 + C = 90 [ from ( 2 ) ]

( 4C + 5C ) / 5 = 90

9C = 450

C = 450 / 9

C = 50

Put C = 50 in ( 2 )

B = ( 4 × 50 ) / 5

B = 4 × 10

B = 40

Therefore ,

A = 90 , B = 40° , C = 50°

I hope this helps you.

:)