SOLUTION: if sides of triangle are 12,15,and 20.find the area of triangle?

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Question 895428: if sides of triangle are 12,15,and 20.find the area of triangle?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Use Heron's formula.
s=%281%2F2%29%2812%2B15%2B20%29=47%2F2
Then,
A=sqrt%28s%28s-12%29%28s-15%29%28s-20%29%29
A=sqrt%28%2847%2F2%29%2847%2F2-12%29%2847%2F2-15%29%2847%2F2-20%29%29
A=sqrt%28%2847%2F2%29%2847%2F2-24%2F2%29%2847%2F2-30%2F2%29%2847%2F2-40%2F2%29%29
A=sqrt%28%2847%2F2%29%2823%2F2%29%2832%2F2%29%287%2F2%29%29
A=sqrt%28128639%2F16%29
A=sqrt%28128639%29%2F4%29