Question

If the height of a triangle is decreased by 40% and it's base is increased by 40%, what will be the effect on its area ?​

Answer 1

Answer:

Let height and base of the triangle be x and y units respectively.

40 % of x=2x5

40 % of y=2y5

Now since x is decreased and y is increased, let

x′=x−2x5

=3x5

y′=y+2y5

=7y5

Therefore the new height is 3x5 and the new base is 7y5 .

Let A=xy2 and A′=3x5×7x52

Dividing A by A′ , we get 2521 . Let the areas be 25 unit 2 and 21 unit 2 .

Percent change =100(final−initial)intial

Therefore percent change in area

=100(21−25)25

−16 %

Therefore area decreases by 16 %.