In the given figure, ∠B >∠C, AQ is the bisector of ∠BAC and AP⊥BC. Prove that angle QAP = 1/ 2∠ b- ∠ c
Answers
Answer:
Step-by-step explanation:
In the figure AQ is bisector of ∠BAC
∠BAQ = x=∠A/2.........(1)
Now ∠A+∠B+∠C=180°
∠A=180°−∠B−∠C
x=∠A/2=90°−∠B/2−∠C/2.......(2)
AD is perpendicular to BC,
∠BAP=90°−∠B.................(3)
Now ∠PAQ=∠BAQ−∠BAP
=x -(90°−∠B)
Putting the values of x from (2)
∠PAQ = 90°−∠B/2−∠C/2 - (90°−∠B)
=90°−∠B/2−∠C/2 - 90°+∠B
∠PAQ =∠B/2−∠C/2
∠PAQ=1/2( ∠B -∠C)
Given : ∠B >∠C, AQ is the bisector of ∠BAC and AP⊥BC
To Find : Prove that ∠QAP = 1/2 (∠B - ∠C)
Solution:
∠A + ∠B + ∠C = 180°
=> (∠A + ∠B + ∠C)/2 = 90°
ABP is right angle triangle
hence ∠BAP = 90° - ∠B
∠BAP + ∠QAP = ∠BAQ
∠BAQ = ∠A/2
=> ∠BAP + ∠QAP = ∠A/2
=> ∠QAP = ∠A/2 - ∠BAP
=> ∠QAP = ∠A/2 - (90° - ∠B)
(∠A + ∠B + ∠C)/2 = 90°
=> ∠QAP = ∠A/2 - ( (∠A + ∠B + ∠C)/2 - ∠B)
=> ∠QAP = ∠A/2 - ∠A/2 - ∠B/2 - ∠C/2 + ∠B
=> ∠QAP = ∠B/2 - ∠C/2
=> ∠QAP = (1/2) (∠B - ∠C)
QED
Hence Proved
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