Which is the equation for a sphere with the center (2,-9,-1) and radius √r? a. (x + 2)2 + (y - 9)2 + ( z - 1)2 = r b. (x - 2)2 + (y + 9)2 + ( z + 1)2 = r c. (x - 2)2 + (y + 9)2 + ( z + 1)2 = √r d. (x + 2)2 + (y - 9)2 + ( z - 1)2 = r2

b.

Step-by-step explanation:

The general equation of a sphere is : , where (a, b, c) represents the center of the sphere, R represents the radius, and x, y, and z are the coordinates of the points on the surface of the sphere.

Given, Center of the sphere =  (2,-9,-1)

Radius = √r

Then, the equation of the sphere would be

Hence, the correct option is b. .

34.5 cm

step-by-step explanation:

generally for a circular segment of angle, θ° and radius r

arc length

= (θ/360) x circumference

= (θ/360) x 2πr

in our case, θ = 60°, π=3.142 and r = 33 cm

substitute into above formula

arc length

= (60/360) x 2(3.142)( 33) = 34.5 cm