Problem: a semicircle is drawn with ab as its diameter . from c , a point on ab , a line perpendicular to ab is drawn , meeting the circumference of the semicircle at d . given that ac = 2 cm and cd = 6 cm , the area of the semicircle in square cm will be ? 
Options: ['a ) 30 pi', 'b ) 40 pi', 'c ) 50 pi', 'd ) 60 pi', 'e ) 70 pi']
c