0/2011 (a)
Prove that cos3x = 4cos'x - 3cos x. Hence, show that
cos2x =-(cos 6x + 3cos 2x).
(b)
[4 marks]
Use the above identity to find all the solutions in the interval
-180° <x<180° of the equation 2 cos 3x + cos2x+1= 0. [7 marks]

good luck!

cutie~

the formula of a slope:

from a table we have

substitute:

the slope of f(x) is -1.

the graph of funcfion g(x) is a horizontal line. the slope of a horizontal line is equal 0. therefore the slope of g(x) is 0.

-1 < 0

the forelimbs below belong to four species that descended in a direct line from the ancestral mammal shown above. of the four descendants shown, which species most likely appeared earliest in evolutionary history?