In actute triangle PQR with PQ = 10m, PR= 15m PQR=40 degree calculate PQR
Answers
Answered by
1
Answer:
Construct PN perpendicular to QR
in triangle PNQ, angle Q=40
so QN=PN
RHS=PQ²+QR²-4*areaPQR
=PN²+QN²+(QN+NR)²-4*0.5*QR*PN
=2PN²+PN²+NR²+2*PN*NR-2*QR*PN
=2PN²+PR²+2PN.NR-2(PN+NR)*PN
=2PN²-2PN²+2PN*NR-2PN*NR+PR²
=PR²=LHS
proved
Similar questions