Q. 65.0( 2 Votes )

# Use a calculator to determine upto two decimal places, the perimeter and the area of the circle in the picture.

Answer :

In the given fig, we can see, BC = 3cm and BD = 6cm

i. Join CD, thus we obtain a diameter CD.

ii. As ∠CBD = 90° (∵ angle in a semi circle is right angle)

Therefore by Pythagoras theorem

BC^{2} + BD^{2} = CD^{2}

3^{2} + 6^{2} = CD^{2}

CD^{2} = 9 + 36 =45

CD = 3√5

Thus, diameter = CD = 3√5

Radius,

iii. Now, change the position of a set square, and draw another diameter to get the center.

Thus, A is a centre.

Hence, radius,

We need to find perimeter of a circle?

We know that,

Perimeter of a circle = 2πr where r = radius

We need to find area of a circle?

We know that,

Area of a circle = π r^{2} where, r = radius

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