(a)[3]
Fill in the table for $y=3\cos 2x^\circ$. Give the values correct to 1 decimal place.
(b)[4]
Sketch the graph of $y=3\cos 2x^\circ$ for $0\le x\le90$.
(c)[1]
From your graph, solve the equation $3\cos 2x^\circ=-2$ for $0\le x\le90$.
(d)[3]
Using a suitable straight line, solve the equation $120\cos 2x^\circ=80-x$ for $0\le x\le90$.