# Find Out the Smallest Angle. If

The measures of two angles of a triangles is in the ratio 4:5. If the sum of these two measures is equal to the measure of the third angle. Find the smallest angle.

- 10
- 40
- 90
- 50

**Answer: (2) 40
Explanation:-
**The ratio of two angles of a triangle = 4 : 5

Let the measure of two angles = 4 X and 5 X

According to the question,

Then, the third angle = 4 X + 5 X = 9X

As we know that the sum of three angle of a triangle is 180

^{o}.

Then, 4 X + 5X + 9X = 180

^{o}

18 X = 180

^{o}

X = 180/18

X = 10

^{o}

Then, the smallest angle is 4 X = 4 x 10

= 40

^{o}

Hence, the answer is (2) 40.