In ΔPQR, PQ = 5 cm, QR = 12 cm and PR = 13 cm, then PQR is 

A) an acute angled triangle

B) a right angled triangle 

C) an obtuse angled triangle 

D) an equilateral triangle

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2 Answers

Correct option is (B) a right angled triangle

\(\because5^2+12^2\) = 25+144

= 169 \(=13^2\)

\(\therefore PQ^2+QR^2=PR^2\) which is a condition that \(\triangle PQR\) is a right angled triangle.

(By converse of Pythagoras theorem)

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B) a right angled triangle

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