help no.2 dan 3 #salammtk

2.a. cos120 -cos300 +sin120
= -cos60 -cos60 + sin 60
=-½-½+✓3/2
= -2+√3/2
b. sin 60x cos 30 + tan 45
= √3/2 x √3/2 + √2/2
= 3/4+√2/2
=3+2√2/4
c. (cos 60 + sin 30)x(cos 60 - sin 30)
= (½+½) x (½-½)
= 0
d.( -tan30 + cos60)/ (-tan30 - cos 60)
= (-√3/3 + √2/2 )/ (-√3/3 - √2/2)
= (-2√3+3√2 / 6) / (-2√3-3√2 /6)
=-2√3+3√2 / -2√3-3√2 ( rasionalkan )
=30-12√6 / 12-18
= 2√6 - 5

3.a. √21