Chapter 6
Measuring Space: Perimeter and Area
CBSE Class 9
Mathematics Solutions
Educart Mathematics class Class 9 NCERT Exemplar cover
Question:

In given figure, semicircles have been drawn on all the sides of a right-angled triangle as shown.

Show that Area (A) + Area (B) = Area (C).

Question image

Answer: Verified

Right-angled triangle with legs aa, bb and hypotenuse cc: a2+b2=c2a^2 + b^2 = c^2

Semicircle A on leg aa: area = (12)π(a2)2=πa28\left(\frac{1}{2}\right)\pi\left(\frac{a}{2}\right)^2 = \frac{\pi a^2}{8}

Semicircle B on leg bb: area = πb28\frac{\pi b^2}{8}

Semicircle C on hypotenuse cc: area = πc28\frac{\pi c^2}{8}

Area(A)+Area(B)=πa28+πb28\text{Area}(A) + \text{Area}(B) = \frac{\pi a^2}{8} + \frac{\pi b^2}{8}

=π(a2+b2)8=πc28=Area(C).= \frac{\pi(a^2 + b^2)}{8} = \frac{\pi c^2}{8} = \text{Area}(C).

Hence, proved.

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