Q5 of 45 Page 43

Find the length of the side and perimeter of an equilateral triangle whose height is cm.


Let ABC be an equilateral triangle,


Let AP be a perpendicular on side BC from A.


To find : Height of triangle = AP


As, ABC is an equilateral triangle we have


AB = BC = CA = 'a'


Also, we know that Perpendicular from a vertex to corresponding side in an equilateral triangle bisects the side



Now, In ΔABP, By Pythagoras theorem


(Hypotenuse)2 = (base)2 + (Perpendicular)2


AB2 = BP2 + AP2





Given,


Height = √3



a = 2 cm


Also, Perimeter of equilateral triangle = 3a


Where 'a' depicts side of equilateral triangle.


Perimeter = 3(2) = 6 cm


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