Answer:
Area decreases by 16%
Step-by-step explanation:
Use formula for the area of the triangle
[tex]A=\dfrac{1}{2}\cdot \text{Base}\cdot \text{Height}[/tex]
Initial triangle:
The base is 18 cm
The height is 5 cm
The area is
[tex]A_{initial}=\dfrac{1}{2}\cdot 18\cdot 5=45\ cm^2[/tex]
New triangle:
The base is [tex](1-0.3)\cdot 18=0.7\cdot 18=12.6\ cm[/tex]
The height is [tex](1+0.2)\cdot 5=1.2\cdot 5=6\ cm[/tex]
The area is
[tex]A_{new}=\dfrac{1}{2}\cdot 12.6\cdot 6=37.8\ cm^2[/tex]
Area decreases by
[tex]100\%-\dfrac{37.8}{45}\cdot 100\%=100\%-84\%=16\%[/tex]
