Answer:
in triangle ACD
<D =<B=90° inscribed angle from the diameter is 90°
base AC=2×OA=2×15=30unit
perpendicular =CD=12unit
area of triangle ACD
=1/2 base×perpendicular=1/2×30×12=180unit²
In triangle ABC
base=AC=30 unit
perpendicular=BC=18unit
area of traingle ABC =
1/2 base×perpendicular=1/2×30×18=270unit²
Area of quadrilateral =area of traingle [ABC+ACD]
=180+270=450 square unit ans..
