Describe in words the surface whose equation is given. r

Five circles are placed in a rectangle as shown. If the length of the shorter side of the rectangle is 1, find the length of the other side.

Two circles, whose radii are 12 inches and 16 inches respectively, intersect. The angle between the tangents at either of the points of intersection is ${\displaystyle {20}^{\circ },{30}^{\prime }}$. Find the distance between the centers of the circle.

Three pipes, each of radius length 4 in., are stacked as shown. What is the exact height of the stack?

If the atomic radius of lead is 0.175 nm, calculate the volume of its unit cell in cubic meters

Two circles have a scale factor of ${\displaystyle 3:2}$. What is the ratio of the areas of these circles?
a) ${\displaystyle 3:2}$
b) ${\displaystyle 9:4}$
c) ${\displaystyle 12:26}$
d) ${\displaystyle 13:12}$

The formula $C=2\pi r$ relates the circumference C of a circle to its radius r.
(a)Solve $C=2\pi r$ for r
(b) If a circle's circumference is 15 inches, what is its radius? leave the symbol $\pi$ in your answer.

a. Are all circles similar?
b. If two circles have radii 9 and 12, what is the ratio of the circumferences? Of the areas?