Scale factor to find the area in similar triangles

The ratio of the areas of two similar figures is equal to the square of the scale factor, k.

∴A_(△PQR)=k^2 A_(△ABC).

You can use this to solve for an unknown area.

Q. The shaded area is to be an industrial zone. Find the area of the industrial zone. Assume that King and Queen are parallel and that all streets and the track are straight.

Q2. If △PQR ~ △STU, find the area of △PQR.