Homework Help: geometry

Posted by justine on Sunday, July 17, 2011 at 2:53am.

the bases of two triangles are the same length. The altitude of the first triangle is 5 cm and the area of the second triangle is 3 times the area of the first. what is the altitude of the second triangle?

geometry - Reiny, Sunday, July 17, 2011 at 8:04am
area of first = (1/2)(b)(5) = 5b/2

area of second = (1/2)(b)(h) = bh/2

but we are told that bh/2 = 3(5b/2)
multiply both sides by 2

bh = 15b
divide both sides by b

h = 15

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