If any of solid in two of intersecting solids is having curves surface that is cylinder, cone, sphere etc line of intersection will give curve only but not straight line for getting line of intersection straight line both solids should not have curved surfaces.

Parallel-line method is employed in case of prisms and cylinders in which stretch out-line principle is used. Radial-line development is used for pyramids and cones in which true length of slant edge or generator is used as a radius.

Parallel-line is employed in case of prisms and cylinders in which stretch out-line principle is used. Radial-line development is used for pyramids in which actual length of slant edge or generator is used as a radius.

Developments of lateral surface of a prism consist of same number of rectangles in contact as number of sides of base of prism. One side of rectangle is equal to length of axis and or side equal to length of side of base.

A number of lines are drawn on lateral surface of one of solids and in region of line of intersection. Points of intersection of se lines with surface of or solid are n located. These points will obviously lie on required line of intersection.

If any of solid in two of intersecting solids is having curves surface that is cylinder, cone, sphere etc line of intersection will give curve only but not straight line for getting line of intersection straight line both solids should not have curved surfaces.

As here a prism and cone are intersected in which prism has plane surface and cone has curved surface and we know curved surface is perpendicular to axis of cone and also given solids intersect at 90 degrees so curve formed will be parallel to axis of a prism.

Approximation method is used to develop objects of double curved or warped surfaces as sphere, paraboloid, ellipsoid, hyperboloid and helicoid. Triangulation method is used for transition pieces. This is simply a method of dividing a surface into number of triangles and transferring m into development.

The development of surface of a cube consists of 6 equal squares, length of side of squares being equal to length of edge of cube. It is 6 squares because cube is bounded by equal squares and only 6 faces are re.

The development of lateral surface of a pyramid consists of a number of equal isosceles triangles in contact. The base and sides of each triangle are respectively equal to edge of base and slant edge of pyramid.