Que: In the Figure, PR > PQ and PS bisect ∠QPR. Prove that ∠PSR > ∠PSQ.
Answers
Solution:
Given, PR > PQ and PS bisects ∠QPR
To prove: ∠PSR > ∠PSQ
Proof:
∠QPS = ∠RPS — (1) (PS bisects ∠QPR)
∠PQR > ∠PRQ — (2) (Since PR > PQ as angle opposite to the larger side is always larger)
∠PSR = ∠PQR + ∠QPS — (3) (Since the exterior angle of a triangle equals the sum of opposite interior angles)
∠PSQ = ∠PRQ + ∠RPS — (4) (As the exterior angle of a triangle equals to the sum of opposite interior angles)
By adding (1) and (2)
∠PQR + ∠QPS > ∠PRQ + ∠RPS
Now, from (1), (2), (3) and (4), we get
∠PSR > ∠PSQ
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Solution:-
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In ∆ PQR
PR > PQ ( Given )
.°. < PQR > <PRQ ---------(1)
( A triangles longest sides of opposite angle is big )
°.° PS , < QPRs a bisect.
.°. < QPS = < RPS
in ∆ PQR ------------(2)
< PQR + < QPS + < PSQ = 180° ----------(3)
( all angles of a triangle equal is 180° )
In ∆ PRS
< PRS + < SPR + < PSR = 180° -------(4)
( all angles of a triangle equal is 180° )
From (3) and (4) ,
< PQR + < QPS + < PSQ = < PRS + < SPR + < PSR
=> < PQR + < PSQ = < PRS + < PSR
=> < PRS + < PSR = < PQR + < PSQ
=> < PRS + < PSR > < PRQ + < PSQ ( From (1) )
=> < PRQ + < PSR > < PRS + < PSQ ( °.° < PRQ = < PRS
=> < PSR > < PSQ
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