The law of cosines :
A^2 = B^2 + C^2 - 2BC cos A
2^2 = 3^2 + 4^2 - 2 . 3. 4 cos theta
= 21
hope this helps
Answer:
1 5/9
Step-by-step explanation:
Answer:
it's estimated that 750 students in the whole school dislike the 8:30am start time.
Step-by-step explanation:
Since 30 of the 40 students said "no", it means 30/40, or 3/4 of the random sample disliked the 8:30am start time. Multiply this by the whole population: 1,000 × (3/4) = 750.
Another way to check this is using 10/40 = .25 and doing 1000x.25 = 250 (the amount of students who liked it). Then subtract from whole population and it's 750.
<em>x</em>/<em>r</em> + <em>x</em>/<em>w</em> + <em>x</em>/<em>t</em> = 1
<em>x</em> (1/<em>r</em> + 1/<em>w</em> + 1/<em>t</em>) = 1
<em>x</em> = 1 / (1/<em>r</em> + 1/<em>w</em> + 1/<em>t</em>)
To make the solution a bit cleaner, multiply through the numerator and denominator by the LCM of each fraction's denominator, <em>rwt</em> :
<em>x</em> = 1 / (1/<em>r</em> + 1/<em>w</em> + 1/<em>t</em>) • <em>rwt</em> / <em>rwt</em>
<em>x</em> = <em>rwt</em> / (<em>rwt</em>/<em>r</em> + <em>rwt</em>/<em>w</em> + <em>rwt</em>/<em>t</em>)
<em>x</em> = <em>rwt</em> / (<em>wt</em> + <em>rt</em> + <em>rw</em>)