## hba Group Title If the radius of a circle is increased by 10 % then the area is increased by, one year ago one year ago

1. tkhunny Group Title

$$\pi r^2$$ $$\pi (r*1.1)^{2} = 1.21\cdot\pi r^{2}$$ What do you think?

2. hba Group Title

@hartnn Yeah lol ? It is a circle but it is a very diff ques..

3. hba Group Title

@tkhunny You are welcome to provide hints and explain

4. tkhunny Group Title

Already did. Radius increased by 10% -- r*1.1 Area is increased by ???

5. hba Group Title

Please explain how did you do the first step

6. tkhunny Group Title

Area of a Circle = $$\pi r^{2}$$, given the radius. That's the first step.

7. hba Group Title

I know that the Area of a circle = pi r^2

8. tkhunny Group Title

New Radius is 10% greater than old radius. R = r*1.1 Area of new circle: $$\pi R^{2}$$.

9. hba Group Title

Got it what next ?

10. tkhunny Group Title

Raio of New Area to Old Area $$\dfrac{\pi R^{2}}{\pi r^{2}}$$.

11. hba Group Title

Ratio*

12. tkhunny Group Title

*Ratio - right A little algebra $$\dfrac{\pi R^{2}}{\pi r^{2}} = \dfrac{R^{2}}{r^{2}} = \dfrac{(1.1\cdot r)^{2}}{r^{2}} = \dfrac{1.1^{2}r^{2}}{r^{2}} = 1.1^{2} = 1.21$$ And we see a 21% increase!

13. hba Group Title

Thank you.