Question

The perimeter of a right triangle is 25 meters, and the area is 20 square meters. The lengths of the sides are each multiplied by 3. What is the area of the new triangle? Please help me, not by just giving me the answer, but by explaining how I solve this so I can solve it on my own. Thanks :)

Answer 1

The Heron's formula for calculating area is
S=√p(p-a)(p-b)(p-c)
where
p is perimiter divided into 2
p=(a+b+c)/2
Then length of each side is multiplyed into 3
New p is bigger than old by three times
p=3(a+b+c)/2  
S=√3p*3(p-a)*3(p-b)*3(p-c)=9√p(p-a)(p-b)(p-c)
Area of new triangle are bigger than area of old triangle by 9 times.
S=20*9=180 square meters
Area of new triangle is 180 square meters.