If the height of a triangle is increased by 30% and its base is decreased by 20%, then what will be the effect on its area?

4% increase

30% = \(\frac{3}{10}\)

20% = \(\frac{1}{5}\)

Area of triangle = \(\frac{1}{2}\) × Base × Height

                           Old              New

Height                  10       :       13

Base                    5         :        4

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Area  =              50        :        52

 Percentage increase in Area = \(\frac{52 - 50}{50}\) × 100%

= \(\frac{2}{50}\) × 100%

= 4%