I assume you're supposed to establish the identity,
cos(A) cos(2A) cos(4A) = 1/8 sin(8A) / sin(A)
Recall the double angle identity for sine:
sin(2<em>x</em>) = 2 sin(<em>x</em>) cos(<em>x</em>)
Then you have
sin(8A) = 2 sin(4A) cos(4A)
sin(8A) = 4 sin(2A) cos(2A) cos(4A)
sin(8A) = 8 sin(A) cos(A) cos(2A) cos(4A)
==> sin(8A)/(8 sin(A)) = cos(A) cos(2A) cos(4A)
as required.
Answer: 18
Step-by-step explanation:
Square root of 81 is 9 because 9*9=81 then 9*2=18
X 1 = 1 ; X 2 = -2
Step-by-step explanation:
We clear the whole numbers, equal to (zero) and use the calculation formula of the quadratic function, according the image:
