It is about finding area want help in part b?

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1 Answer
May 4, 2018

Given triangle ABC is a equilateral triangle, one interior angle is pi/3π3.

Since the 3 arcs are equal,
/_CAB=pi/3CAB=π3
2alpha = pi/32α=π3

Since /_AOB = 2pi/3AOB=2π3 and AO=OB=rAO=OB=r,
Triangle AOB is a equilateral triangle.
:. r=4

Substitute 2alpha = pi/3 and r=4 into the answer for (a)(ii),
Area of segment AB
=1/2r^2(pi/3-sin(pi/3))
= 1/2(4)^2(pi/3-sqrt(3)/2)
= (8pi)/3-4sqrt(3)

Area of triangle ABC
=1/2a b sinC
=1/2(4)(4)(sin(pi/3))
=4sqrt(3)

Area of shaded region
= Area of triangle ABC - 3 Area of segment AB
=4sqrt(3)-3((8pi)/3-4sqrt(3))
=4sqrt(3)-8pi+12sqrt(3)
=16sqrt(3)-8pi