Not understood

Saahil, this is a basic geometry question. Area of a triangle = ½ · base · height. This question tricks you into thinking the base is 15 and the height is 9. Actually, the height is the side that is perpendicular to the base (9). Using Pythagorean theorem, you can calculate the height from 9^2 + h^2 = 15^2, h = 12. Now you can plug it into the area formula.

How do I know the base is 9?

Thank you

Beverly, for calculating the area, the base can be any of the sides of the triangle, but it has to be perpendicular to the line we pick as the height, which extends to a tip of the triangle.

In this example, the side equal to 9 is already known to be perpendicular to the other side (which we will conveniently pick as the height).

You can, of course, pick 15 as the base. But then you have to calculate the line from that side, that is perpendicular to the bottom side, shooting up to the peak of the triangle -- which is a problem since we don't have enough information to do so.

I understand when you get the root but after that about length I did not understand in question 20

Please review the previous discussion thread carefully to understand the steps.