The total surface area of the solid object is the sum of the surface area of the cylinder and the surface area of the cone.
The surface area of the cylinder is 2πr(r+h), where r is the radius of the cylinder and h is its height.
The surface area of the cone is πr(l+r), where r is the radius of the cone and l is its slant height.
Since the cylinder and the cone have the same radius, we can call this radius r.
The total surface area of the solid object is therefore 2πr(r+h) + πr(l+r).
We are told that this total surface area is equal to 6336/210 = 30 sq. cm.
Thus, we can set up the equation: 2πr(r+h) + πr(l+r) = 30.
We are trying to find the value of l, which is the slant height of the cone. We are given the value of h, which is the height of the cylinder. We can substitute this value into the equation to get:
2πr(r+30) + πr(l+r) = 30.
This equation can be rearranged and solved for l to find the slant height of the cone.
l = sqrt(900 - 60r).
Since we are given that the slant height of the cone is 26 cm, we can substitute this value into the equation to solve for the radius of the cone:
26 = sqrt(900 - 60r)
Solving for r, we find that the radius of the cone is 15 cm.
Substituting this value back into the equation for the slant height of the cone, we find that the height of the cone is:
l = sqrt(900 - 60(15)) = sqrt(300) = 17.67 cm.
Thus, the height of the cone is approximately 17.67 cm.