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August 22, 2014

August 22, 2014

Posted by **Sandy** on Monday, October 13, 2008 at 5:49pm.

- Math -
**Damon**, Monday, October 13, 2008 at 6:06pmThat will not work because you do not know the altitude of the triangle. You must get the area of the triangular base from the lengths of the three sides.

To find the altitude from the 21 cm base:

call the part next to the 10 cm leg x

call the part next to the 14 cm leg (21-x)

call the altitude h

then

x^2 + h^2 = 100

(21-x)^2 + h^2 = 196

so

(21-x)^2 -x^2 =96

441 - 42x = 96

42 x = 345

x = 8.214

x^2 = 67.47

100-x^2 = 32.5 = h^2

h = 5.7

so

(1/2)h *21 = 59.9 = area of base triangle

multiply by 30 to get volume

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