" i) "cos3B=4cos^(3)B-3cos B

Derivative of cos^(-1)(4cos^(3)x-3cos x) is (A) 1 (B) 2 (C) 3 (D) 4

Show that in any Delta ABC, a ^(3) cos 3B+3a^(2)b cos (2B-A)+3ab^(2) cos (B-2A) +b^(3) cos 3A =c^(3)

In triangle ABC if A=60^(@) , show that cos^(2)B+ cos^(2)C+ cos B cosC =(3)/(4) .

If A+B+C=pi and if cos3A+cos3B+cos3C=1 then show that one angle must be 120^@.

ig sin B=(1)/(2) then prove that 3cos B-4cos^(3)B=0

In a triangle ABC if sin B=(1)/(2)=cos A then 3cos B-4cos^(3)B=(i)sin C(ii)cos C(iii)0(iv)3(sqrt(3))/(2)

If cos A+ cos B + cos C =0 then cos 3A+ cos 3B + cos 3X

If three angles A,B,C are such that cos A+ cos B+cos C=0 and if lambda cos A cos B cos C=cos3A+cos3B+cos3C ,then value of lambda is :

If sin B = 0.5, find the value of 3 cos B-4cos^(3)B