This is a maths question..please help

A semicircular object has a perimeter of 180 cm. Find the area ,in cm,of the object

1
Sesiapa mahu tuisyen online math upsr pt3 dan spm bole ws saya 017-2847059 ..beri nama dan umur ye di ws 
thx
betul x jwpn saya

Jawapan

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2016-09-13T13:24:37+08:00
R = A / tetha
r = 180 - d / 180°

180° × tetha/180 = 3.1416
d/2 = 180 - d / 3.1416
3.1416d = 360 - 2d
5.1416d = 360
d = 70
r = 70÷2
r = 35

Area = 1/2 × pie × r^2
= 1/2 × pie × 35^2
= 1924.2255 cm^2
1 5 1
which equation
d/2 = 180 - d / 3.1416
and find d
to get radius,u just divide d by 2
ok