Question

14 Two angles of a triangle are in the ratio 4:5. If the sum of these angle is equal to the 3rd

angle. Find the angle of triangle?​

Answer 1

A/Q

4x+5x=3rd angle

9x=3rd angle

So,

1st angle+ 2nd angle+ 3rd angle=180

4x+5x+9x=180

18x=180

x=180/18

x=10

So,

1st angle=4x=4×10=40°

2nd angle=5x=5×10=50°

And,

3rd angle=sum of these angles

40°+50°=90

PROVED✓✓

Answer 2

let the given 2 angles be 5x&4x and the 3rd angle be "y"

According to the problem

4x+5x+y=180

9x=180-y(since sum of all angles in a triangle is 180)

9x+y=180

given y=4x+5x

y=9x

9x+9x=180(since y=9x)

18x=180

x=10

therefore; 4x= 4(10)=40

5x=5(10)=50

9x=9(10)=90

verification:-

9x=4x+5x

9(10)=4(10)+5(10)

90=40+50

90=90

hence proved.

Hope it helps you.....