geometry

[sunilrawat]

Side AB of triangle ABC lies on the diameter of circle O as shown in the figure above. Half of the height to side AB equals 4/5 of the radius of the circle.
If the area of triangle ABC is 90, what is the closest approximation to the area of semicircle AOB?
35
45
88
180
350


I didn't understand the question. What does the bolder part mean ?
Though I solved it like this:
Approximating area of part of the triangle inside the circle as (90/2), I chose the answer as 88

[cans]

radius = 6. base of abc = 2r and h = 8r/5 (half height to AB = 4r/5)
thus area = (1/2)bh = 8* r^2 / 5 = 90 -> r = 5 * 3 /2 = 15/2
area of semicircle = pi* r^2 /2 = (22/7) (225/8) = 11*225 / 28 = 2475/28 around 88
IMO C

[force5]

that statement means- that if Height of the triangle is H and if R is the radius of the circle then

H/2 = 4/5R

also given is 1/2 AB *H= 90

where AB = 2R

substituting the values you will get R = 15/2
and area of semicircle approx 88