Question

Sin 65+ cos 65 = -square root 2 cos 20

Answer 1

Answer:

write question properly........

Answer 2

Answer:

Heya mate your answer

Step-by-step explanation:

Now,

cos20

= cos (65 - 45)

= cos65 cos45 + sin65 sin45

= cos65 (1/√2) + sin65 (1/√2)

=> cos65 + sin65 = √2 cos20

=> sin65 + cos65 = √2 cos20

Hence, proved.

We used the identity rule -

cos (A - B) = cosA cosB + sinA sinB