a) Correct.
b) Area of rectangle is one side multiplied by the other.
One of the sides is 2x as it's x one way from the origin and x the other way.
You've already worked out the length of the other side. You did it in part a).
Figure here shows a rectangle inscribed in an isosceles right triangle whose hypotenuse is 2 units long.
a. Express the y coordinate of P in terms of x. I get 1 - x ... Correct?
b. Express the area of the rectangle in terms of x. Not sure how to go about solving this one.