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Question : 69 of 160
Marks:
+1 ,
-0
Solution:
The expression for PQ is expressed as,
P Q = ( b + c + a ) − ( b + c + a ) = ( b − a ) + ( c − b ) + ( a − c ) The expression for PR is expressed as,
P R = ( c − a ) + ( a − b ) + ( b − c ) Then,
P Q . P R = a 2 + b 2 + c 2 − a b − b c − c a The magnitude of
P Q is
| P Q | = √ ( b − a ) 2 + ( c − b ) 2 + ( a − c ) 2 The magnitude of
mathrm ‌ P R is,
| P R | = √ ( c − a ) 2 + ( a − b ) 2 + ( b − c ) 2 Then,
cos ‌ θ = cos ‌ θ = θ = © examsiri.com
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