Free help with homework

Why join Brainly?

  • ask questions about your assignment
  • get answers with explanations
  • find similar questions

If the height of a triangle is decreased by 40% and its base is increased by 40% the effect on its area is:

no change
8% decrease
16% decrease


The area of a triangle is given by, A=\frac{1}{2}bh,
The change in area (if there is any) is given by, (1+\frac{\delta A}{A})=(1+\frac{\delta b}{b})(1+\frac{\delta h}{h}).
Here, \frac{\delta b}{b}=+0.4 and \frac{\delta h}{h}=-0.4.
Hence, \frac{\delta A}{A}=-0.16.
Therefore, Area decreases by 16%.
1 5 1

This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
Let initial base=b,
area, A₁ = 0.5 bh

after height is decreased by 40% and base is increased by 40%,
base = 1.4b
height = 0.6h
Area, A₂ = 0.5×1.4b×0.6h = 0.42 bh

A₂ - A₁ = 0.42 bh - 0.5 bh = -0.08 bh
-ve sign indicates that area decreased.

% decrease = (0.08bh/0.5bh)×100 = 16%
3 5 3
The Brain
  • The Brain
  • Helper
Not sure about the answer?
Learn more with Brainly!
Having trouble with your homework?
Get free help!
  • 80% of questions are answered in under 10 minutes
  • Answers come with explanations, so that you can learn
  • Answer quality is ensured by our experts