Question

Halo friends please give me answer​

Answer 1

Answer:

8+8cos⁶10+24cos²10+24cos⁴10

Step-by-step explanation:

We know that x³+y³+3xy(x+y) is an identity which is written as (x+y)³

So,

(x+y)³=(cos²5+cos²10+cos²15+sin²5+cos²10+sin²15)³

        =([sin²5+cos²5]+[sin²15+cos²15]+[cos²10+cos²10])³

        =(2+2cos²10)³

        =8+8cos⁶10+24cos²10+24cos⁴10      [by expanding identity]

This is the final answer. However if you meant to put sin²10 instead of cos²10 in y then the final answer would have been 27.