Example 7
Find the altitude of a right triangle with area 50 sq.ft. and base 8 ft.
Solution:
Area of a right triangle = 
50 = 
\ altitude = 12.5 sq.ft.
Example 8
Find the area of the trapezoid ABCD.
Solution:
Area of the trapezoid ABCD = 
= 12 cm2
Example 9
Find the circumference of a circle with area 25 p sq. ft.
Solution:
Area of the circle = p r2 = 25 p
\ r = 5 ft.
\ circumference = 2 pr
= 10 p
Example 10
Find the area of a circle with circumference 30p cm.
Solution:
Circumference = 2 p r = 30 p
r = 15 cm
area = p r2
= p ´ 152
= 225 p
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