Your computer's screen saver is an expanding circle. The circle starts in the middle of the screen and expands outwards. With a 21 inch screen, you have a viewing area of a 10 inch radius. The circle reaches the corners in 4 seconds, expanding at a rate of 2.5 inches per second. Use this information to answer the next three questions. 4. Express the radius of the circle, r (in inches), as a function of time, t (in seconds). (A) r(t) =2.5t (B) r(1) = 2.5n (C) r(t) = 2.5+2 (D) r(t) =2.5nt (E) r(t) = 2.5nt2 5. Express the area of the circle, A, as a function of the radius, r (in inches). (A) A(r) =5r2 (B) A(r) = 2.5712 (C) A(r) =6.25712 (D) A(r) =6.25r2 (E) A(r) = mr 6. Evaluate (A or )(3), and give a practical interpretation. (A) (Aor)3)=18.75m. After 3 seconds, the area of the circle is 18.757 square inches. (B) (Aor)(3)=102.25m . After 3 seconds, the area of the circle is 102.257 square inches. (C) (Aor)3) =18.75. After 3 seconds, the area of the circle is 18.75 square inches. (D) (Aor)3)=56.25. After 3 seconds, the area of the circle is 56.25 square inches. (E) (Aor)3) = 56.25m . After 3 seconds, the area of the circle is 56.25m square inches