Assuming CB is 6 cm also
you have a triangle area = 1/2 b h = 1/2* 6 * 6 cm2
and a semi circle = 1/2 pi r^2
= 1/2 pi (3^2) cm^2 radius = 1/2 diameter = 1/2 * 6 = 3
Add the reds for area ......
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Perimeter : find hypotenuse of right triangle sqrt ( 62 + 62) = sqrt 72 = 6 sqrt 2 cm
plus the base 6 cm
plus the semicircle 1/2 * pi * 6 cm Add the reds for perimeter