Question

The sum of the measures of the angles of a triangle is 180. The sum of the measures of the second and third angles is four

times the measure of the first angle. The third angle is 10 more than the second. Let , y, and z represent the measures of
the first, second, and third angles, respectively. Find the measures of the three angles.

Answer 1

9514 1404 393

Answer:

(36°, 67°, 77°)

Explanation:

The problem statement lets us write the equations ...

x + y + z = 180 . . . . sum of angles in a triangle

y + z = 4x . . . . . 2nd and 3rd total 4 times the first

z = y +10 . . . . . . 3rd is 10 more than 2nd

__

Substituting for z in the second equation, we have ...

y +(y +10) = 4x

y +5 = 2x . . . . . . divide by 2

y = 2x -5 . . . . . . rearranged

z = 2x +5 . . . . . . substitute for y in the last equation

Now, we can write the first equation entirely in terms of x:

x +(2x -5) +(2x +5) = 180

5x = 180

x = 36

y = 2(36) -5 = 67

z = 67 +10 = 77

The three angles are (x, y, z) = (36°, 67°, 77°).