单选题
In the flat triangular surface depicted above, if 
feet, what is the area of the surface in square feet? (Figure not necessarily drawn to scale.)
feet, what is the area of the surface in square feet? (Figure not necessarily drawn to scale.)
【正确答案】
E
【答案解析】Since the leg of the right triangle is 
and the hypotenuse is x, we can tell that it is a 30-60-90 triangle and that the other leg is x12. The area of a triangle is 1/2 base times height, so the area is 
and since we know that 
feet and therefore x2=6 square feet, the area is 
.
and the hypotenuse is x, we can tell that it is a 30-60-90 triangle and that the other leg is x12. The area of a triangle is 1/2 base times height, so the area is and since we know that feet and therefore x2=6 square feet, the area is .