# Math Help - Solution of triangles problem

1. ## Solution of triangles problem

given triangle pqr where pqr is an obtuse angle.given that qr=10.5cm,pq=8cm and the area of pqr is 21 cm^2.find degree of q..

2. Originally Posted by mastermin346
given triangle pqr where pqr is an obtuse angle.given that qr=10.5cm,pq=8cm and the area of pqr is 21 cm^2.find degree of q..
The area of the triangle PQR is calculated by:

$a = \dfrac12 \cdot |\overline{PQ}| \cdot |\overline{PR}| \cdot \sin(Q)$

Plug in the values you know and solve for sin(Q). Keep in mind that Q > 90°.