SOLUTION: the area of a circke varies directly as the square of its radius. a circle of radius 5 inches has area 78.5 square inches. find the area to the nearest tenth of a circle of radius

Question 30760: the area of a circke varies directly as the square of its radius. a circle of radius 5 inches has area 78.5 square inches. find the area to the nearest tenth of a circle of radius 7 inches.
Answer by ikdeep(226) (Show Source): You can put this solution on YOUR website!
this question can be directly solved by applying the formula...
area of circle = ∩(pie) r^2
= 22/7 * (7)^2
= 22/ 7 * 49
= 22 * 7
= 154 square inches
but I think your question demands to apply direct variation method here ...so if we find it by direct variation then we get equation...
(5)^2 /78.5 =(7)^2 / x [x here is area of circle which u wish to find out]
on solving it we get x = 153.86 or 154 (appoximately)
Still if you won't be able to solve further, contact me again.
hope this will help you
Please feel free to revert back for any further queries.

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