In the attached figure, ST=5cm & QR=9cm. The area of the larger triangle is 50 sq.cm. What is the area of the black region?

Thanks,

Ron

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- Dec 15th 2009, 12:09 AMrn5aArea of triangle
In the attached figure, ST=5cm & QR=9cm. The area of the larger triangle is 50 sq.cm. What is the area of the black region?

Thanks,

Ron - Dec 15th 2009, 01:20 AMearboth
- Dec 15th 2009, 03:14 AMjgv115
The problem is how to find the height of the whole triangle..

- Dec 15th 2009, 09:23 PMearboth
Honestly I don't understand why you want to know the height of the triangle QRP because you already know that the area of the this triangle is 50 cm².

But: Since you know that $\displaystyle \overline{QR} = 9\ cm$ you can use the value of the area and the length of the base to calculate the length of the height:

$\displaystyle 50 =\frac12 \cdot 9 \cdot h~\implies~ h= \frac{100}9$

And now? - Dec 15th 2009, 09:25 PMjgv115
I should learn to read.

- Dec 15th 2009, 10:07 PMLochcelious
I thought you just subtract the area of the smaller traingle from the triangle of the whole to get 27.5 sq.cm?