Question

verify cos3A=4cos³A-3cosA, when A=30⁰​

Answer 1

Step-by-step explanation:

If A  =30∘

cos3A=Acos3A−3cosA

cos90∘=4(cos30∘)2−3(cosA30∘)

0=4.(23)=23.3

0=4.2×2×233−233

0=233−233

0 =0

LHS = RHS

Hence proved

Answer 2

Answer:

cos 30 leke solve karo = √3/2

cose ke place pe ye value put kar n ans nikal jayega