The measure of one angle of a triangle is five times that of a second angle, and the measure of an exterior angle at the third vertex is 120. Find the measure of angle of a triangle.

Answer 1

Hi

If you mean't to say that

The measure of the first angle in a triangle is 5 times the measure of the second angle in the triangle and the measure of the third angle in the triangle is 120 degrees then

Since the sum of the angles in a triangle is 180

You could

Let the first angle = a

Let the second angle = b

Let the third angle = c

If the interpretation of the information given is correct then

a = 5b (the first angle is 5 times the second angle)

b = b

c = 120

5b + b + 120 = 180

6b + 120 = 180

Subtract 120 from both sides of the equation

6b = 60

Divide both sides by 6

b = 10 the second angle in the triangle

5b = 50 = a the first angle in the triangle

Checking

10 + 50 + 120 = 180

Please let me know if I have interpreted your information correctly. I hope this helps