Question

Tentukan nilai dari sin 150°- sin 120°/cos 300° - cos 210° !

Answer 1

Sn 150 = sin(180-30) = sin 30 = 1/2
sin 120 = sin(180-60) = sin 60 = 1/2√3
cos 300 = cos (360- 60) = cos 60 = 1/2
cos 210 = cos(180+30) = - cos 30 = -1/2√3

( sin 150 - sin 120) / (cos 300 - cos 210)=
= (1/2 - 1/2√3) ./ (1/2 + 1/2 √3)
= 1/2 ( 1 - √3) / 1/2( 1 + √3)
= (1 - √3)/ (1 + √3)
= (1 - √3)(1 -√3)/ ( 1 - 3)
= (1+3 - 2√3) / (-2)
= (4 - 2√3) / (-2)
= - 2 +√3
= √3 - 2
..