The shaded rectangle in the diagram consists ofthree squares. (Picture for full question)

 243 cm²

Step-by-step explanation:  If the diameter is 18, the radius is 9. Each square is  9×9, so 81 cm² for each.   Multiply:  81×3 = 243

Or take the length times width  to get area  27×9= 243

c.   x=2.4cm

step-by-step explanation:

similar triangles are triangles which have the same shape but not the same size. this means their angle measures are equal but their side lengths are not instead they are proportional. to solve, we will set up a proportion and solve.

a proportion is two equal ratios set equal to each other. we form the ratios by finding corresponding sides (sides which match to each other on both triangles by their position). out ratios will be one side of the small triangle over the corresponding side on the big triangle as shown below:

.

to solve the proportion, we'll cross multiply by multiplying numerator with denominator across the equal sign.