The following may involve the use of the sine Rule as well C

The following may involve the use of the sine Rule as well Cosine Rule. In the given ABC, D is a point on [BC] |BD| = 6 cm, |AC| = 9 cm, |

Solution

10. In triangle ADC, <ADC=180-(50+80)=50

Using sine law which is

sin <ADC/AC=sin<DAC/DC

sin 50/6= sin50/DC

DC=6

ii. AB

Using cosine law which is

AB²=AC²+BC²-2 AC BC cos <ACB

AB²= 9²+15²-2(9)(15)cos80

AB²=81+225 - 270cos 80

AB= 16cm