Sin 15 = p, maka sin 75 =.... Maaf nge blur... tolong pake caranya plis...

sin 15 = depan/miring = y/r =  p/1 = p
cos 15 = samping/miring = x/r = ?

Gunakan pytagoras untuk mencari "samping"
x = √(r² - y²)
x = √(1² - p²)
x = √(1 - p²)

Maka,
cos 15 = √(1 - p²)/1 = √(1 - p²)

Kemudian cari sin 75,,
sin 75
= sin(60 + 15)
= sin60.cos15 + cos60.sin15
= 1/2√3.√(1 - p²) + 1/2.p
= 1/2√3 - 1/2√3p² + 1/2p
= 1/2(√(3 - 3p²) + p)