The curved surface area of a cone is 4070cm2 and its diameter is 70 cm. What is its slant height (in cm) ?
We know, the curved surface area of a cone =πrl, where r is the radius of the cone and l is the slant height.
Given, curved surface area of cone =4070cm2 and diameter d=70cm.
Therefore, Radius r=d2=702=35 cm.
Hence, curved surface area of this cone =227×35×l
⇒227×35×l=4070 ⇒l=7×407022×35
⇒l=37 cm .