if the measures of the angles of a triangle are in the ratio 1:3:5 , the number of degrees in the measure of the smallest angle is

a. 10
b. 20
c. 60
d. 180

answer is b. 20

To find the measures of the angles in a triangle when given their ratios, we need to determine the sum of the angle measures.

Let's assume that the measures of the angles are 1x, 3x, and 5x, where x is a constant.

The sum of the angle measures in a triangle is always 180 degrees.

Therefore, we can set up the equation: 1x + 3x + 5x = 180.

Simplifying the equation, we have 9x = 180.

Dividing both sides of the equation by 9, we get x = 20.

Now we can substitute the value of x back into the measures:

Smallest angle = 1x = 1 * 20 = 20 degrees.

Therefore, the answer is option b. 20 degrees.