Question

PQR is a triangle, right angled at P. If PQ= 3 cm and PR=4cm,find QR
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Answer 1

Here we'll use Pythagoras theorem

h² = p² + b²

QR² = 3² + 4²

QR² = 9 + 16

QR² = 25

QR = 5

Answer 2

Given: A triangle PQR, right angled at P

           PQ = 3 cm and PR = 4 cm

To find: QR

Solution: Using Pythagoras theorem,

.: $(Hypotenuse)^{2}$ = $(Perpendicular)^{2}$ + $(Base)^{2}$

QR is the hypotenuse (Side opposite to the right angle is called hypotenuse)

PQ is the perpendicular (Side perpendicular to the base)

PR is the base (Side on which right angled triangle stands)

Using the theorem,

$(QR)^{2}$ = $(PQ)^{2}$ + $(PR)^{2}$

⇒ $(QR)^{2}$ = $(3)^{2}$ + $(4)^{2}$

⇒ $(QR)^{2}$ = 9 + 16 = 25

⇒ QR = $\sqrt{25}$ = 5

The value of QR is 5 cm.