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RD Sharma Solutions Class 8 Mathematics Solutions for Understanding Shapes Polygons Exercise 15.1 in Chapter 15 - Understanding Shapes Polygons
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How many diagonals does each of the following have?
(i)A convex quadrilateral
(ii)A regular hexagon
(iii)A triangle
Answer:
(i)A convex quadrilateral
For a convex quadrilateral we shall use the formula n(n-3)/2
So, number of diagonals = 4(4-3)/2 = 4/2 = 2
A convex quadrilateral has 2 diagonals
(ii)A regular hexagon
For a regular hexagon we shall use the formula n(n-3)/2
So, number of diagonals = 6(6-3)/2 = 18/2 = 9
A regular hexagon has 9 diagonals.
(iii) A triangle
For a triangle we shall use the formula n(n-3)/2
So, number of diagonals = 3(3-3)/2 = 0/2 = 0
A triangle has no diagonals.
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