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In a triangle ABC THE internal bisectors of angle B and angle C meet at p and the external bisectors of angle B and angle C meet at Q prove that angle BPC +angle BQC =180 |
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Answer» Answer: ANSWER ∠ABC+ext.∠∠ABC=180 o 2 1
(∠ABC+ext.∠ABC)=90 o
∠PBC+∠QBC=90 o (PB BISECT Interior ∠B, QB BISECTS ext.∠B) ∠PBQ=90 o
Similarly, ∠PCQ=90 o
Sum of angles of QUADRILATERAL PBCQ =360 o
∠BPC+∠PBQ+∠PCQ+∠BQC=360 o
∠BPC+∠BQC=180 o
∴∠BPQ+∠BQC = 2 rt. angles |
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