perimeter = add all 3 sides 13+13+10 = 36 cm
for area you need to find the height of the triangle, which is the red dotted line
to do that use the Pythagorean Theorem
a^2 + B^2= c^2
a^2 = height
a^2 +5^2 = 13^2
a^2 +25 = 169
a^2 = 169-25 = 144
a=square root(144) = 12
so the height is 12
area = 1/2 h x b = 1/2 x 12 x 10 = 1/2x 120 = 60
area = 60 cm^2
cost is $4 per square cm
there is 60 square cm in the triangle so multiply 60 x 4 = $240