BPSC 53-55th Exam Prelims 17 Apr 2011 Solved Paper

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Question : 79 of 150

Marks: +1, -0

In triangle

P Q R

if

∠ P=120^{∘}

and

P Q=P R

then

∠ Q

and

∠ R

will be respectively

$60^{∘}, 30^{∘}$
$30^{∘}, 40^{∘}$
$30^{∘}, 30^{∘}$
$20^{∘}, 40^{∘}$

Solution:

From the question,

P Q=P R

∠ {Q}=∠ {R}

{P}+ {Q}+ {R}=180^{∘}

⇒ ∠ Q+∠ Q=180^{∘}-∠ P

⇒ ∠ Q=\;{180^{∘}-120^{∘}}/{2}=30^{∘}

∴ ∠ R=30^{∘}

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