The surface area of a right cone is 400.2 m2. the radius of the cone is 6.0 m. determine the height of the cone to the nearest metre.

                 S = πr(r + √(h² + r²))
          400.2 = 3.14(6)(6 + √(h² + 6²))
          400.2 = 18.84(6 + √(h² + 36))
          18.84                 18.84
        21¹⁰⁹/₄₇₁ = 6 + √(h² + 36))
        - 6         - 6
        15¹⁰⁹/₄₇₁ = √(h² + 36)
231²²¹⁰⁰⁵/₂₂₁₈₄₁ = h² + 36
- 36                       - 36
195²²¹⁰⁰⁵/₂₂₁₈₄₁ = h²
                14 ≈ h

    6.64

 -  1.35

 = 5.29 

To the nearest tenth it is 5.3 times more miles of coastline.