SOLUTION: The height of a triangle is four times the length of the base. Find the base and height of the triangle if the area is 18 square inches.

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Question 123780: The height of a triangle is four times the length of the base. Find the base and height of the triangle if the area is 18 square inches.
Found 2 solutions by checkley71, MathLover1:
Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
a=bh/2
a=b*4b/2
18=4b^2/2
36=4b^2
36/4=b^2
9=b^2
3=b answer.
4*3=12 for the height.
proof
18=3*4*3/2
18=36/2
18=18

Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!
Given:
the height: h
the base: b
the area A is 18+in%5E2
if he height of a triangle is four times the length of the base, then we have:
h+=+4b
A+=+%281%2F2%29bh
18+in%5E2+=+%281%2F2%29b%2A4b
18+in%5E2+=+4%281%2F2%29b%5E2
18+in%5E2+=+cross%284%292%281%2Fcross%282%29%29b%5E2
18+in%5E2+=+2b%5E2
18+in%5E2%2F2+=+b%5E2
9+in%5E2+=+b%5E2
sqrt%289+in%5E2%29+=+b
b+=+3+in+
then h+=+4b…=>…h+=+4%2A3inh+=+12in
Check:
A+=+%281%2F2%29bh
A+=+%281%2F2%293in%2A12in
A+=+%281%2Fcross%282%29%293in%2Across%2812%296in
A+=+3in%2A6in+
A+=+18in%5E2+