Question

O is the centre of the circle such that diameter ab 10cm and ac8cm find the area of the semi circle

Answer 1

area of a circle:pi r^2

" " semicircle :pi r^2 /2

:25pi

Answer 2

Given,
diameter ab = 10cm
radius of the circle =10/2 =5cm
Acb is the angle in the semi circle
so,ACB=90°
now, in ACB we use Pythagoras theorem,
AB^2=AC^2+BC^2
(10)^2=(8)^2+BC^2
BC^2= 100-64
BC^2=36
BC=6
Now area of semi circle,
1/2 π r^2
1/2 ×22/7×25=39.28