question_answer

The figure shows an isosceles triangle and a semicircle with centre O. Given that the radius of the semicircle is 2.8 cm, find the perimeter of the given figure.

A)  15.6cm                                

B)  18.8cm

C)  16.8cm                

D)         20.4cm

Correct Answer: B

Solution :

  Circumference of circle\[\text{4}0={{\text{2}}^{\text{3}}}\times \text{5}\] \[\text{6}0={{\text{2}}^{\text{2}}}\times \text{3}\times \text{5}\] \[\therefore \]Circumference of semicircle = 8.8 cm \[={{2}^{2}}\times 3\times 5\times 2=120\]Perimeter of the given figure = (5 + 5 + 8.8) = 18.8 cm