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8 years, 6 months ago
8 years, 1 month ago
Let CE be the perpendicular on AD.
Now AC = 8^2 - 4 = rt60(Angle in a semi cirlce is right angle so we can use pythagoras theorem)
Now area of the triangle ACD = 1/2*2*rt60 = rt60 = 1/2*8*x => x = rt15/2
Now, In triangle EDC,
By pythagoras theorem ED^2 = 4 - 15/4 = .25
=> ED = .5
Thus BC = 8 - 2*.5= 7 cm
Hope that helps.