Posted by Marisa on Tuesday, June 15, 2010 at 3:49pm.
What is the radius if the area of the circle is:
4x^2(PI)
My answer 4x^2(pi)=(pi)(r)(2), 16x(pi)=(pi)(r)(2), 16x/pi=5x.
5(PI)
My answer 5(pi)=(pi)(r)(2), sqare root of 5 is 2.23, which rounds to 3, 3(pi)=square root of 9.
What is the area of the sector if the radius is 6 and the degree measure is:
30
My answer 30/360(pi)(6)^2, 0.83(pi)(36),rounds to 1(pi).
50
My answer 50/360[(pi)6^2], 7.1/72[(pi)36], 7.1(36), 255/3.14, =81, square root of 81=9*pi.
90
My answer 90/360[(pi)6^2] 9.49/72[(pi)(36)], 18/9=2*pi.
120
My answer 120/360[(pi)6^2], 4/72[(pi)(36)] 4(36)=144, square root of 144=12*pi.
These are the question and answers that were incorrect on my assignment. I am unsure of what I did incorrect. I would be grateful for assistance. Cheers!
Sincerely,
Marisa

Geometry  Reiny, Tuesday, June 15, 2010 at 5:28pm
first one:
πr^2 = 4x^2 π
r^2 = 4x2
r = 2x
if area = 5P
πr^2 = 5π
r^2 = 5
r = √5
sector angle=60°, r = 6
area = (30/360)(π)(36) = 3π
for sector angle=50°
area = (50/36)(36π) = 5π
the rest are the same