Question 7 Two cones with same base radius 8 cm and height 15 cm are joined together along their bases. Find the surface area of the shape so formed.
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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: Radius of cone, r = 8cm and Height of cone, h = 15 cm
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×πrl=2×π×r×√r2+h2(l=√r2+h2)=2×227×8×√(8)2+(15)2=2×22×8×√64+2257=44×8×√2897=59847=854.85cm2=855cm2(approx) Hence , the surface area of shape so formed is 855cm2