aniruddhawarang29
TestPrepUnlimited
Bunuel
What is the maximum possible area of a triangle with a side of length 7 units and another side of length 8 units?
A. 14 square units
B. 21 square units
C. 28 square units
D. 56 square units
E. 64 square units
We can treat 8 as the base, if 7 were to be another length of the triangle then the highest area possible is when 7 is the height. Any other angle between 8 and 7 that is not a right angle, results in a height less than 7. Then the area is \(8*7/2 = 28\).
Ans: C
But why is the third side not considered here?
The third side can be in the range of 1<x<15.
For the area to be max the base and height need to be max numbers of these three i.e 7,8 and
14So area comes out to be 8*14/2 = 56.
Pls rectify if I am not on the right track.
You can intuitively imagin that when you make the third side bigger, the height of the triangle is smaller and then the area is smaller (obviously it won't be a right triangle). You can also see that the same happens when the third side is small.
Using Heron's formula of the area of a triangle using lengths of the sides we have:
A = 0,25*sqrt(−x^4+226x^2−225)
being x the length of the third side.
If you draw that function you can see that the maximum is at x = sqrt(113). Which is the same length that we obtain supposing that it is a right triangle with x as the hypotenuse.