Principle Of Mathematical Induction

Question

The area of a triangle is 75 square cm. If sides AB = 20 cm, AC = 15 cm, find ∠A.

Solution

Using formula,
   $space space space Area space of space ΔABC space equals space 1 half bcsinA comma$ , we have
   $WiredFaculty$
$rightwards double arrow$    $space space space sinA space equals space fraction numerator 75 cross times 2 over denominator 20 cross times 15 end fraction equals 1 half$
$rightwards double arrow$ $angle straight A space equals space 30 degree space or space 150 degree$