Question

13. A figure is made up of a triangle ABD and a semicircle.
BOD is the diameter of the semicircle with
centre 0. If AB = AD = 5.7 cm, BD = 7 cm and
AOC = 8 cm, find
B
(1) the perimeter,
(ii) the area,
of the figure.
С 7 cm o
5.7 cm
A
D
8 cm
323
Chapter 13 Perimeter and Area of Plane Figures​

Answer 1

If ∟A= 60° then,

∟B+∟C = 180–60 = 120°

Further, AB = AC then,

∟B = ∟C = 120°/2 = 60°

It is an equilateral triangle. Let s be the side of triangle .

AB=BC=AC =s

A semicircle is drawn with radius r, diameter BC and angle subtended θ,

Length of arc = r x θ

r= diameter /2 = BC/2 = s/2

Length of the semicircle = 50π (given)

50π= (s/2) θ

comparing corresponding values,

s/2 =50

s=100

Perimeter = 3s = 3 x 100 = 300

Ans: Perimeter of the triangle is 300 units

Answer 2

Step-by-step explanation:

pls solve the question