Question

prove that cos 20 * cos 40 * cos 80 = 1/8

Answer 1

Which of the following best describes the graph of f(x) = x ^2 - 7x + 10?

Minimum at (1.5, -12.25) with intercepts at (5, 0) and (-2, 0)

Minimum at (-1.5, -12.25) with intercepts at (-5, 0) and (2, 0)

Minimum at (-3.5, -2.25) with intercepts at (-5, 0) and (-2, 0)

Minimum at (3.5, -2.25) with intercepts at (5, 0) and (2, 0)

Answer 2

poop

Answer 3

i need help here not poop

Answer 4

L.H.S = cos 20 * cos 40 * cos 80
= 2*sin(20)*cos20*cos40*cos80 / (2sin20)
= sin(40)*cos(40)*cos(80)/(2sin20)
= sin(80)*cos(80)/(4sin20)
=sin160 / ( 8 sin20)
= sin(180-20)/(8sin20)
=sin20/(8sin20)
=1/8
= R.H.S