9514 1404 393
Answer:
12. (x, D, E, F) = (8, 38°, 75°, 67°)
13. (x, P, Q, R) = (13, 126°, 30°, 24°)
Explanation:
The sum of angles in a triangle is 180°. We choose to write the equations assuming all measures are degrees.
12. (5x -2) +(9x +3) +(11x -21) = 180
25x = 200 . . . . . . . add 20, simplify
x = 8 . . . . . . . . . divide by 25
Then the angle measures are ...
∠D = 5(8) -2 = 38°
∠E = 9(8) +3 = 75°
∠F = 11(8) -21 = 67°
__
13. (10x -4) +(4x -22) +(x +11) = 180
15x = 195 . . . . . . . . . . add 15, simplify
x = 13 . . . . . . . . . divide by 15
Then the angle measures are ...
∠P = 10(13) -4 = 126°
∠Q = 4(13) -22 = 30°
∠R = 13 +11 = 24°