Question

reese needs a new bike mirror. her old mirror was a rectangle with a length of 10 cm and a width of 5 cm. she wants the new mirror to have approximately the same area as the old mirror. which circular bike mirror should reese buy? three circular bike mirrors with radii 4 cm, 7 cm, 8 cm respectively

Explanation:

Step1: Calculate old mirror area

Area of rectangle = length × width = $10 \times 5 = 50$ cm²

Step2: Find radius for each circle

For diameter 4 cm: radius $r = 2$ cm
For diameter 7 cm: radius $r = 3.5$ cm
For diameter 8 cm: radius $r = 4$ cm

Step3: Calculate circle areas

Area of circle = $\pi r^2$

• 4 cm diameter: $\pi (2)^2 ≈ 12.57$ cm²
• 7 cm diameter: $\pi (3.5)^2 ≈ 38.48$ cm²
• 8 cm diameter: $\pi (4)^2 ≈ 50.27$ cm²

Step4: Choose closest area

50.27 cm² is closest to 50 cm², so pick 8 cm diameter mirror.

Answer:

The circular bike mirror with a diameter of 8 cm