28. Jika sin 48 = 0,743 , cos 48 = 0,669, sin 127 = 0,799, cos 127 = -0,602, carilah nilai dari tg 79

first, tan(48) = sin(48)/cos(48) = 0,743/0,669 = 1,11
tan(127) = sin(127)/cos(127) = 0,799/-0,602 = - 1,33


tan79 = tan(127 - 48)
= (tan127 - tan48)/(1+tan127tan48)
= (-1,33 - 1,11)/(1 + (-1,33)(1,11)
= (-2,44)/(1 - 1,47)
= -2,44/-0,47
= 5,1

cara lain, gunakan calculator ..... ;v