Question

jika A, B dan C adalah sudut sudut pada segitiga ABC, maka tunjukkan bahwa

a. sin (A+B) = sin C

b. cos 1/2 (A+B) = sin 1/2C

c. Tg (A+B) = -tg C

Answer 1

A.
sin(a + b) = sin(c)
sin(a + b) = [a + b + c = π]
sin(a + b) = [c = π - (a + b)]
sin(a + b) = [sin(c) = sin (π - (a + b))]
sin(a + b) = [sin(c) = sin(a + b)]
sin(a + b) = sin(a + b)

b.
c.