Quick Homework Help

A right triangle with side lengths 3 cm, 4 cm, and 5 cm is similar to a right triangle with a 20-cm hypotenuse. Find the perimeter of the larger triangle. PLEASE HELP ME! ⚑ Flag

by WolvesofJesonae at February 24, 2011

I already know that the larger triangle is the one with the 3, 4, and 5 cm side legnths because it has a 25 cm hypotenuse. But what I don't know is how to find the perimeter of a traingle. HEEELP MEEE PLEEEAAASEEE!!!

to find the perimeter of a triangle you just add up all the sides. just like with a rectangle or square. so add 3+4+5 and you get 12. so the perimeter of the trangle is 12 cm.

tori. February 24, 2011

The triangle with sides 3,4,5 is the smaller triangle, keep in mind Pythagoras theorem a^2 + b^2 = c^2. the hypotenuse is 5 in the first triangle (3^2+4^2=5^2). With that in mind, the second triangle is the same as the first just larger, if we enlarge the first triangle to make the hypotenuse is 20 then we would also increase the other sides by the same ratio (4:1) multiply each side by 4 to get 12, 16, 20 then add together to get the perimeter 48.to test this I can calculate 12^2+16^2=20^2 and I find this to be a true statement because 12^2= 144 and 16^2=256 and 20^2=400, 144+256=400

kieth003 February 24, 2011

48; the other triangle has 4x the side length of the small triangle (3-4-5) the hypotnuse of bigger triangle is 20 and hypotnuse of smaller is 5 so there is a 4x more. So  the other two legs are 12(3X4) and 16 (4x4) so add all three sides to get perimeter of 48 cm

GURUKID February 24, 2011

If you set up a ratio of hyp. to whole perimeter, that should work.

Ashley564 February 24, 2011

you can also just set up a proportion

loiujk February 24, 2011