Question

In ΔABC, if a = 18, b = 24, c = 30 then find the values of sinA.

Answer 1

Given: a = 18, b = 24 and c = 30

`cos A = (b^2+c^2-a^2)/(2bc)`

`cos A = (24^2+30^2-18^2)/(2xx24xx30)`

= `(576+900-324)/1440`

= `1152/1440`

= `4/5`

`sin^2 A = 1-cos^2 A`

= `1 - (4/5)^2`

= `1- 16/25 = 9/25`

= `sinA = sqrt(9/25)`

= `3/5`