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 three times the measure of the first angle. The third angle is 21 more than the second. Let x, y, and z represent the measures of the first, second, and third angles, respectively. Find the measures of the three angles.

Answer 1

(x, y, z) = (45°, 57°, 78°)

Explanation:

The problem statement tells you ...

x + y + z = 180

-3x +y +z = 0

0x -y +z = 21

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Subtracting the second equation from the first gives ...

4x = 180

x = 45 . . . . . . divide by 4

Substituting this into the first equation and adding the third equation gives ...

(45 +y +z) +(-y +z) = (180) +(21)

2z = 156 . . . . simplify, subtract 45

z = 78 . . . . . . divide by 2

y = z -21 = 57

The angle measures are ...

(x, y, z) = (45°, 57°, 78°)