Question

if cos10cos30cos50cos70+k=0 find k​

Answer 1

Answer:

k = -3/16.

Step-by-step explanation:

cos10cos30cos50cos70+k = 0

=> cos10cos30cos50cos70 = -k.

=> √3/2cos10. 1/2(cos120+cos20)

=> √3/4(Cos(180-60).cos10 + cos10.cos20)

=> √3/4((-cos60)*cos10 + cos30+cos10/2)

=> √3/4(-1/2cos10 + 1/2(cos30+cos10))

=> √3/8(-cos10+√3/2+cos10)

=> √3/8(√3/2) = 3/16.

=> k = -3/16.