tolong bantu jawab no. 21 ya... secepatnya

sinA=1/2√2=45 derajat
tanB=-1/3√3=150 derajat
cos(A-B)=cosAcosB+sinAsinB
=cos45*cos150+sin45*sin150
=1/2√2*-1/2√3+1/2√2*1/2
=-1/4√6+1/4√2
maaf kalo salah

sin A = 1/2 √2
A lancip --> A = 45°

tan B = -1/3 √3
B tumpul --> B = 150°

cos (A - cos B)
= cos 45° cos 150° + sin 45° sin 150°
= 1/2 √2 . -1/2 √3 + 1/2 √2 . 1/2
= 1/4 (-√6 + √2)

Opsi E