Question

Evaluate: cos3A-2cos4A /sin3A +2sin4A when A=15degree​

Answer 1

Answer:

(cos3a-2cos4a)/(sin 3a+2sin4a)= (put a = 15)

(cos 45 -2cos60)/((sin45+2sin60)=

(1/√2-1)/(1/√2+ √3)

= (1-√2)/(1+√6)

=(1-√2)/(√6+1)

=(1-√2)(√6-1)/((√6+1)(√6-1))

=(1-√2)(√6-1)/5 Ans