Addition Formulae : Examples

 

 

 

 

 

 

 

 

 

 

 

 

 

 

In triangle ABC, show that the

exact value of

 

 sin(a+b) is

 

(Higher 2002, Paper 1)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1.    Rearrange to set equation to zero. 2.    Eliminate the Cos2x˚ term, turning the equation into  a quadratic. 3.    Factorise 4.    Solve each set of brackets. 5.    Remember to combine answer at end !