Prove that cos(4x) = 8(cos^4(x))-8(cos^2(x)) + 1
cos(4x) = cos(2(2x)) = 2(cos^2(2x)) - 1 = 2 (cos^2(x) - 1)^2 - 1 = 8(cos^4(x)) - 8(cos^2(x)) + 1
HT
Related Maths A Level answers
All answers ▸The curve C has equation: (x-y)^2 = 6x +5y -4. Use Implicit differentiation to find dy/dx in terms of x and y. The point B with coordinates (4, 2) lies on C. The normal to C at B meets the x-axis at point A. Find the x-coordinate of A.
Find the first and second derivative of f(x) = 6/x^2 + 2x
Differentiate with respect to x: (x^2+5)^3
A curve has equation x = (y+5)ln(2y-7); (i) Find dx/dy in terms of y; (ii) Find the gradient of the curve where it crosses the y-axis.