Please solve q 12 ?

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1 Answer
May 13, 2018

#anglePQR=112.5^@#

Explanation:

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Sum of interior angles of a pentagon #=3xx180=540^@#,
given that #angleA=angleB=angleD=90^@, and angleC=angleE#,
#=> angleC=angleE=(540-3xx90)/2=135^@#,
As#angleABC=90^@, => angleKBC=180-90=90^@#,
given #PQ# bisects #angleKBC, => angleQBC=(angleKBC)/2=90/2=45^@#,
as #angleBCD=135^@,=> angleLCD=180-135=45^@#
given #QR# bisects #angleLCD#,
# => angleRCD=angleRCL=(angleLCD)/2=45/2=22.5^@#,
In #DeltaBQC, angleBQC=180-45-22.5=112.5^@#

Hence, #anglePQR=angleBQC=112.5^@#