Question

Please help me! The diameter of the smaller circle is d. The diameter of the larger circle is d+1.

a) Write an expression that represents the area of the smaller circle in terms of d.

b) Write an expression that represents the area of the larger circle in terms of d.

c) Write and simplify an expression that represents the area of the shaded part of the diagram in terms of d.

d) If d represents 10 cm, find the area of the shaded part of the diagram, to the nearest tenth of a square cm.

Answer 1

Is it a) A = pi(1/2d)^2?

Answer 2

Area of a circle = pi * r^2 (where r is radius). Since diameter is twice radius, you should be able to write the expression in terms of d.

Answer 3

Correct.

Answer 4

Larger circle has a diameter of (d+1). Same expression formula applies, but with d+1 for diameter.

Answer 5

ohhh, okay. Thank you :)