Loading http://wiki.math.se/jsMath/fonts/msam10/def.js
To print higher-resolution math symbols, click the
Hi-Res Fonts for Printing button on the jsMath control panel.

jsMath

Solution 4.1:9

From Förberedande kurs i matematik 1

Revision as of 12:30, 27 September 2008 by Ian (Talk | contribs)
Jump to: navigation, search

10 seconds corresponds to 61 minutes, so that during that time period, the second hand sweeps over 61 of a turn, i.e. the sector of a circle with angle


\displaystyle \alpha =\frac{1}{6}\centerdot 2\pi radians \displaystyle =\frac{\pi }{3} radians


The area of the sector is

Area \displaystyle =\frac{1}{2}\alpha r^{2}=\frac{1}{2}\centerdot \frac{\pi }{3}\centerdot \left( 8\ \text{cm} \right)^{2}=\frac{32\pi }{3}\ \text{cm}^{2}\approx 33.5\ \text{cm}^{2}