In a right circular cone ,height ,radius and slant height do not always be side of a right triangle.

Explanation

True
On rotating a right -angled triangled lamina AOB about OA, it generates a cone. The point A is the vertex of a cone. Its base is a circle with centre O and radius OB. The length OA is the height of the cone and the length AB is called its slant height.

Clearly , `angle AOB = 90^(@)`
Let the radius of the bases = r units, height = hunits
and Slant height = l units, then
`l^(2) = h^(2) + r^(2) rArr l = sqrt(h^(2) +r^(2))`
Hence, in a right circule cone, height radius and slant height do not always be side of a right triangle.