8 . The following diagram shows a triangle ABC and a sector BDC of a circle with centre B . The points A , B and D are on the same line .
C
A B D
AB � 1.75r , AC � 1.5r , BC � r , r � 0 , ABC ˆ is acute .
( a ) ( i ) Show that cos ACB ˆ � 0.0625 .
( ii ) Hence , find ˆ sin ACB .
It is given that the area of the triangle ABC is 7 .
( b ) Find r .
( c ) ( i ) Find ˆ ABC .
( ii ) Hence , find the area of the sector BDC .
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