What is the area of a triangle whose sides are 5,5, and 6?
Here’s that triangle:
You know you need a triangle’s height to calculate its area, and you know (or if you didn’t, you do now) that when you draw a vertical like that in an isosceles triangle, you make a perpendicular bisector to the base.
If you know your Pythagorean Triples well enough, you’re already done. You should always be on the lookout for 3-4-5 triangles on the SAT. The height of the triangle is 4, and its base is 6. The area, then, is .