yg jago matematika bantu saya dong no 77, 78

77. (D)
p : q = 1 : 4
p + q = 180°
q = 4/(1+4) x 180 = 720/5 = 144°
r = 144 - 90 = 54°


78. ( A )
A = 7/5 B
A+B = 90°
7B/5 + 5B/5 = 90°
12B/5 = 90°
B = 5x90/12 = 37,5°

besar sudut = 90-37,5 = 52,5° = 52°30'