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In A B C ,P is an interior point such t...

In ` A B C ,P` is an interior point such that `/_P A B=10^0/_P B A=20^0,/_P C A=30^0,/_P A C=40^0` then ` A B C` is isosoceles (b) right angled equilateral (d) obtuse angled

A

isosceles

B

right angled

C

equilateral

D

obtuse angled

Text Solution

Verified by Experts

The correct Answer is:
A


From `Delta APB, Delta PBC, and Delta PCA`, using sine rule
`(AP)/(sin angleABP) (BP)/(sin anglePCB) .(CP)/(sin angle PAC)`
`= (AP)/(sin anglePCA) .(CP)/(sin anglePBC).(BP)/(sin anglePAB)`
`rArr sin30^(@) .sinx .sin 10^(@) = 2in 20^(@) .sin (80^(@) -x) sin 40^(@)`
`rArr x = 60^(@)`
`:. angle BCA = angle CAB = 50^(@)`
So, `DeltaABC` is an isosceles triangle
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