©G Dear2008 – Not to be sold/Free to use General Mathematic (HSC) Further Trigonometry Sine Rule - Angle Stage 6 - Year 12 Press Ctrl-A ©G Dear2008 – Not to be sold/Free to use

The Sine Rule – Finding an Angle (1/2) c b B a C Sin A a Sin B b Sin C c = = To use the Sine Rule to find an angle … we need two angles and … the sides opposite them.

The Sine Rule – Finding an Angle (2/2) Sin A a Sin B b A = 4 cm Sin A 5 X 5 Sin 40 4 X 5 = 5 x Sin 40 4 Sin A = 40o 5 cm Sin-1 ( ) 5 x Sin 40 4 A = ≈ 54o