Question

10. Find the perimeter and the area of the shaded region in the adjoining figure, it
being given that OAB is an equilateral triangle of side 28 cm and one end is a
semi-circle on AB as diameter.
(Take 3 = 1.73)
​

Answer 1

Step-by-step explanation:

area=(1/2)*28*28 +(1/2)*3.14*14*14

=392+307.72

=699.72 cm^2

Answer 2

$\sf{Given}$

• side of equilateral triangle(a)=28cm
• radius of semi-circle(r)= 28/2 = 14cm

$\longrightarrow\:{Perimeter}$

$\\\implies \sf3\times28+ \frac{2\pi r}{2} \\\implies \sf84 + \frac{22}{7} \times 14\\ \\ \implies \sf 84+44\\ \implies \sf128 cm$

$\longrightarrow\:{Area}$

$\implies \sf\frac{ \sqrt{3} }{4} {a}^{2} + \frac{\pi {r}^{2} }{2} \\ \implies \sf\frac{ \sqrt{3} }{4} \times 28\times 28+\frac{1}{2} \times \frac{22}{7} \times 14 \times 14 \\ \implies \sf 196\sqrt{3} + 308 cm$