Question and Answers Forum

All Questions      Topic List

Algebra Questions

Previous in All Question      Next in All Question      

Previous in Algebra      Next in Algebra      

Question Number 103094 by I want to learn more last updated on 12/Jul/20

.

$$. \\ $$

Commented by I want to learn more last updated on 12/Jul/20

The area of a circle is increasing at the rate of 4cm²/s. Find the rate of change of the circumference when the radius is 6cm.

Commented by I want to learn more last updated on 12/Jul/20

Please workings sir

$$\mathrm{Please}\:\mathrm{workings}\:\mathrm{sir} \\ $$

Commented by Dwaipayan Shikari last updated on 12/Jul/20

A=πr^2   (dA/dt)=π.2r(dr/dt)⇒4=π.12(dr/dt)⇒(1/(3π))=(dr/dt)  (dC/dt)=2π.(dr/dt)⇒(dC/dt)=(2/3)cm/s  C=circumference

$${A}=\pi{r}^{\mathrm{2}} \\ $$$$\frac{{dA}}{{dt}}=\pi.\mathrm{2}{r}\frac{{dr}}{{dt}}\Rightarrow\mathrm{4}=\pi.\mathrm{12}\frac{{dr}}{{dt}}\Rightarrow\frac{\mathrm{1}}{\mathrm{3}\pi}=\frac{{dr}}{{dt}} \\ $$$$\frac{{dC}}{{dt}}=\mathrm{2}\pi.\frac{{dr}}{{dt}}\Rightarrow\frac{{dC}}{{dt}}=\frac{\mathrm{2}}{\mathrm{3}}{cm}/{s}\:\:{C}={circumference} \\ $$

Commented by I want to learn more last updated on 14/Jul/20

Thanks sir

$$\mathrm{Thanks}\:\mathrm{sir} \\ $$

Terms of Service

Privacy Policy

Contact: info@tinkutara.com