### Tuesday, October 24, 2006

Year 13 Hints

1 a What is cos x? b What is sin x?

2 Find 3x first.

3 Use the appropriate identity to produce a quadratic in tan x.

4 See the examples before exercise 7D.

5 Multiply both the numerator and denominator by sin x.

6 Use the double angle formulas. Use the appropriate versions of cos 2x so that the ones cancel.

7 Factorise both the numerator and denominator.

8 Factorise and then write with a common denominator.

9 a You can't simplify fg(x).

b Swap x and y, then rearrange. c ditto!

10 This is a quadratic equation.

11 Is there an asymptote?

12 Remember: for an inverse to exist every value of y must have only one value of x.