Question
Two cones with same base radius 8cm and height 15cm are joined together along their bases. Find the surface area of the shape so formed.
✓
Answer
If two cones with same base and height are joined together along their bases, then the shape so formed is look like as figure shown.
Given that, radius of cone, r = 8cm and height of cone, h = 15cm So, surface area of the shape so formed = Curved area of first cone + Curved surface area of second cone = 2.Surface area of cone [since, both cones are identical] $=2\times\pi\text{rl}=2\times\pi\times\text{r}\times\sqrt{\text{r}^2+\text{h}^2}$ $=2\times\frac{22}{7}\times8\times\sqrt{(8)^2+(15)^2}$ $=\frac{2\times22\times8\times\sqrt{64+225}}{7}$ $=\frac{44\times8\times\sqrt{289}}{7}$ $=\frac{44\times8\times17}{7}$ $=\frac{5984}{7}=854.85\text{cm}^2$ $=855\text{cm}^2\ (\text{approx})$ Hence, the surface area of shape so formed is $855cm^2.$
Given that, radius of cone, r = 8cm and height of cone, h = 15cm So, surface area of the shape so formed = Curved area of first cone + Curved surface area of second cone = 2.Surface area of cone [since, both cones are identical] $=2\times\pi\text{rl}=2\times\pi\times\text{r}\times\sqrt{\text{r}^2+\text{h}^2}$ $=2\times\frac{22}{7}\times8\times\sqrt{(8)^2+(15)^2}$ $=\frac{2\times22\times8\times\sqrt{64+225}}{7}$ $=\frac{44\times8\times\sqrt{289}}{7}$ $=\frac{44\times8\times17}{7}$ $=\frac{5984}{7}=854.85\text{cm}^2$ $=855\text{cm}^2\ (\text{approx})$ Hence, the surface area of shape so formed is $855cm^2.$
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