- #1

Taylor_1989

- 402

- 14

I would just like to someone to have a quick look at my maths for this question. I do not feel 100% that I am doing it right.

Question: Two circles have a radii r cm and 4r cm.

Find in terms of ∏ and r

a) the area of the circle with radius 4r. Here are my working; by the way still cant get latex to work, I have tried to everything, could someone point me to a latex post to see where I am going wrong.

area = ∏*r^2 ====> ∏*(4r)^2 =====> (16∏r^2)

b) The area of the shaded ring:

area = 16∏r^2 - ∏r^2 = (15∏r^2)

c) The total length of the inner and outer edges of the shaded ring.

Circumference = 2∏r =====> 2∏4r ======> 8∏r =====> 8∏r + 2∏r = (10∏r)

The answers and the ones with brackets. I have attched a drawing of the image that goes with the question. Not sure if really needed.

Question: Two circles have a radii r cm and 4r cm.

Find in terms of ∏ and r

a) the area of the circle with radius 4r. Here are my working; by the way still cant get latex to work, I have tried to everything, could someone point me to a latex post to see where I am going wrong.

area = ∏*r^2 ====> ∏*(4r)^2 =====> (16∏r^2)

b) The area of the shaded ring:

area = 16∏r^2 - ∏r^2 = (15∏r^2)

c) The total length of the inner and outer edges of the shaded ring.

Circumference = 2∏r =====> 2∏4r ======> 8∏r =====> 8∏r + 2∏r = (10∏r)

The answers and the ones with brackets. I have attched a drawing of the image that goes with the question. Not sure if really needed.