Unit 2 Revision Exercise 4

Trig Graphs and Equations

1. Solve for

2cos(2x) + 6sin(x) –4 = 0

2. Draw the graphs of cos(2x) + 1 and –cos(x) and find algebraically the points of intersection.

3. For y = sin() – sin() 0

find a) y when x =

b) x when y = -

4. Show that sin( 90 – a) = cos(a)

Hence or otherwise show that for the isosceles triangle below

a = and so a = 2bsin(x)

5.

A

a) Show that BD = cos(x)

b) Show that AB² = 1 + 3cos²(x) and hence that AB² = ½(3cos(2x) + 5)