In right triangle ABC, AC is the hypotenuse. If AcC is 40 and AB + BC = 50, what is the area of the triangle ABC?
A. 225
B. 450
C. 25√2
D. 200
E. 200√2
The OA is A.
I'm confused with this PS question. Please, can any expert assist me with it? Thanks in advanced.
In right triangle ABC, AC is the hypotenuse. If AC is 40...
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We have a right triangle whose hypotenuse is 40, and whose sides sum to 50. We want the area.LUANDATO wrote:In right triangle ABC, AC is the hypotenuse. If AcC is 40 and AB + BC = 50, what is the area of the triangle ABC?
A. 225
B. 450
C. 25√2
D. 200
E. 200√2
The OA is A.
I'm confused with this PS question. Please, can any expert assist me with it? Thanks in advanced.
Let's call the two sides of the triangle x and y. The area will be xy/2.
We know x + y = 50, and if 40 is the hypotenuse
x^2 + y^2 = 40^2.
Let's take x + y = 50 and square both sides to get (x +y)^2 = 50^2. We can expand to get x^2 + 2xy + y^2 = 50^2.
We want xy/2. Look at our two equations
1) x^2 + 2xy + y^2 = 50^2.
2) x^2 + y^2 = 40^2
Notice that if we subtract the second from the first, we'll be left with an xy term. Terms in red will cancel out.
x^2 + 2xy + y^2 = 50^2.
- x^2 + y^2 = 40^2
____________________________
2xy = 50^2 - 40^2 ---> difference of squares!
2xy = (50 + 40)(50 - 40)
2xy = 90 * 10 = 900
xy = 450
xy/2 = 225.
The answer is A