Question

The external radius and height of a hollow metal cylinder, 1.5 cm thick are 6.75 cm and
15 cm respectively. A solid cylinder of height 7.5 cm is made by melting this hollow cylinder. Find the radius of the solid cylinder.​

Answer 1

Actually, I don't know the write answers but here is hw you can find the radius of a circle.

The radius of a circle can be found using the three basic radius formulas i.e., when the diameter, the area, or the circumference is known. Let us use these formulas to find the radius of a circle.

• When the diameter is known, the formula for the radius of a circle is: Radius = Diameter / 2

• When the circumference is known, the formula for the radius is: Radius = Circumference / 2π

• When the area is known, the formula for the radius is: Radius = ⎷(Area of the circle / π)

Radius of a Circle Equation

Observe the diagram of a circle in the cartesian plane shown below. The coordinates of the center are (h, k). The radius of a circle equation in the cartesian coordinate plane is given by (x − h)2 + (y − k)2 = r2. Here, (x, y) are the points on the circumference of the circle that are at a distance ‘r’ (radius) from the center (h, k). When the center of the circle is at origin (0,0), the equation of the circle reduces to x2 + y2 = r2