Question

Find the numerical value of the expression
sin 45 cos 45 + sin 30 cos 60 -cos^{2} 30

Answer 1

Greetings from Brasil...

According to trigonometry, we have:

COS α = SIN (90 - α)

SIN α = COS(90 - α)

Then

(SIN 45).(COS 45) + [(SIN 30).(COS 60)] - COS² 30]

(√2/2).(√2/2) + [(1/2).(1/2)] - (√3/2)² = 0