Cos 300 derajat kali Cos 30 derajat per Tan 315 derajat

(cos (300) × cos (30)) / tan (315)

cos 300 = 1/2
cos 30 = 1/2 (akar 3)
tan 315 = sin (315) / cos (315)
= -(1/2)(akar 2) / (1/2)(akar 2) = -1

(1/2) × (1/2)(akar 3) / -1
= - 1/4 (akar 3)