Q. 55.0( 1 Vote )

Q and R of a triangle PQR are 25° and 65°. Is PQR a right-angled triangle? Moreover, PQ is 4cm and PR is 3 cm. Find QR.

Answer :

In ΔPQR, Q = 25° and R = 65°.

We know that sum of angles of a triangle = 180°.


P + Q + R = 180°


P + 25° + 65° = 180°


P = 180° - 90°


P = 90°


Δ PQR is a right angled triangle which is right angled at P.


Given, PQ = 4 cm and PR = 3 cm



We know that in a right-angled triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides.


In ΔPQR, QR2 = PQ2 + PR2


QR2 = 42 + 32


= 16 + 9


= 25


QR = √25 = 5 cm


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