All Solutions
Section 6-1: Radian Measure
$pi radians$;
$cancel{pi radians}timesleft(dfrac{180^{circ}}{cancel{pi radians}} right)=180^{circ}$
#### (b)
$dfrac{pi}{2} radians$;
$dfrac{cancel{pi}}{2}timesleft(dfrac{180^{circ}}{cancel{pi radians}} right)=90^{circ}$
#### (c)
$-pi radians$;
$-cancel{pi radians}timesleft( dfrac{180^{circ}}{cancel{pi radians}}right)=-180^{circ}=180^{circ}$
#### (d)
$-dfrac{3pi}{2} radians=dfrac{pi}{2} radians$;
$-dfrac{3cancel{pi}}{2} cancel{ radians}timesleft(dfrac{180^{circ}}{cancel{pi radians}} right)=-270^{circ}$
$-2pi radians$;
$-2cancel{pi radians}timesleft( dfrac{180^{circ}}{cancel{pi radians}}right)=-360^{circ}$
#### (f)
$dfrac{3pi}{2} radians$;
$dfrac{3cancel{pi}}{2}cancel{radians}timesleft(dfrac{180^{circ}}{cancel{pi radians}} right)=270^{circ}$
#### (g)
$-dfrac{4cancel{pi}}{3}cancel{radians}timesleft( dfrac{180^{circ}}{cancel{pi radians}}right)=-240^{circ}$
#### (h)
$dfrac{2pi}{3} radians$;
$dfrac{2cancel{pi}}{3}timesleft( dfrac{180^{circ}}{cancel{pi radians}}right)=120^{circ}$
$75^circ=75^circ(dfrac{pi radians}{180^circ})=dfrac{5pi}{12} radians$
#### (b)
$200^circ=200^circ(dfrac{pi radians}{180^circ})=dfrac{10pi}{9} radians$
#### (c)
$400^circ=400^circ(dfrac{pi radians}{180^circ})=dfrac{20pi}{9} radians$
#### (d)
$320^circ=320^circ(dfrac{pi radians}{180^circ})=dfrac{16pi}{9} radians$
$dfrac{5pi}{3}=dfrac{5pi}{3}timesleft(dfrac{180^{circ}}{pi radians} right)=300^{circ}$
#### (b)
$0.3pi=0.3pitimesleft(dfrac{180^{circ}}{pi radians} right)=54^{circ}$
#### (c)
$3=3timesleft(dfrac{180^{circ}}{pi radians} right)=171.89^{circ}$
#### (d)
$dfrac{11pi}{4}=dfrac{11pi}{4}timesleft(dfrac{180^{circ}}{pi radians} right)=495^{circ}$
$5=dfrac{x^{circ}}{360^{circ}}(2pi)(2.5)$
$1800=(x)(2pi)(2.5)$
$114.6^{circ}=x$
$114.6^{circ}=^{circ}timesleft( dfrac{pi radians}{180^{circ}}right)=2 radians$
#### (b)
$200^{circ}=200^{circ}timesleft(dfrac{pi radians}{180^{circ}} right)=dfrac{10 pi}{9} radians$
$x=dfrac{dfrac{10pi}{9}}{2pi}(2pi)(2.5)$
$x=dfrac{5}{9}(2pi)(2.5)$
$x=dfrac{25pi}{9}$ cm
$3.5=3.5timesleft( dfrac{180^{circ}}{pi radians}right)=200.5^{circ}$
$x=dfrac{200.5^{circ}}{360^{circ}}(2pi)(8)$
$x=28$ cm
#### (b)
$300^{circ}=300^{circ}timesleft( dfrac{pi radians}{180^{circ}}right)=dfrac{5pi}{3} radians$
$x=dfrac{dfrac{5pi}{3}}{2pi}(2pi)(8)$
$x=dfrac{5}{6}(2pi)(8)$
$x=dfrac{40pi}{3}$ cm
$90^{circ}=90^{circ}timesleft( dfrac{pi radians }{180^{circ}}right)=dfrac{pi}{2} radians$
#### (b)
$270^{circ}=270^{circ}timesleft(dfrac{pi radians}{180^{circ}} right)=dfrac{3 pi}{2} radians$
#### (c)
$-180^{circ}=-180^{circ}timesleft(dfrac{pi radians}{180^{circ}} right)=-pi=pi radians$
#### (d)
$45^{circ}=45^{circ}timesleft( dfrac{pi radians}{180^{circ}}right)=dfrac{pi}{4} radians$
#### (e)
$-135^{circ}=-135^{circ}timesleft(dfrac{pi radians}{180^{circ}} right)=-dfrac{3pi}{4}=dfrac{5pi}{4} radians$
#### (f)
$60^{circ}=60^{circ}timesleft(dfrac{pi radians}{180^{circ}} right)=dfrac{pi}{3} radians$
#### (g)
$240^{circ}=240^{circ}timesleft( dfrac{pi radians}{180^{circ}}right)=dfrac{4pi}{3} radians$
#### (h)
$-120^{circ}=-120^{circ}timesleft(dfrac{pi radians}{180^{circ}} right)=-dfrac{2pi}{3}=dfrac{4pi}{3}radians$
$dfrac{2pi}{3}=dfrac{2pi}{3}timesleft( dfrac{180^{circ}}{pi radians}right)=120^{circ}$
#### (b)
$-dfrac{5pi}{3}=-dfrac{5pi}{3}timesleft( dfrac{180^{circ}}{pi radians}right)=-300^{circ}=60^{circ}$
#### (c)
$dfrac{pi}{4}=dfrac{pi}{4}timesleft(dfrac{180^{circ}}{pi radians} right)=45^{circ}$
#### (d)
$-dfrac{3pi}{4}=-dfrac{3pi}{4}timesleft( dfrac{180^{circ}}{pi radians}right)=-135^{circ}=225^{circ}$
#### (e)
$dfrac{7pi}{6}=dfrac{7pi}{6}timesleft( dfrac{180^{circ}}{pi radians}right)=210^{circ}$
#### (f)
$-dfrac{3pi}{2}=-dfrac{3pi}{2}timesleft( dfrac{180^{circ}}{pi radians}right)=-270^{circ}=90^{circ}$
#### (g)
$dfrac{11pi}{6}=dfrac{11pi}{6}timesleft( dfrac{180^{circ}}{pi radians}right)=330^{circ}$
#### (h)
$-dfrac{9pi}{2}=-dfrac{9pi}{2}timesleft( dfrac{180^{circ}}{pi radians}right)=-810^{circ}=-90^{circ}=270^{circ}$
$x=dfrac{dfrac{19pi}{20}}{2pi}(2pi)(65)$
$x=dfrac{19}{40}(2pi)(65)$
$x=dfrac{2470pi}{40}$
$x=dfrac{247pi}{4}m$
#### (b)
$1.25=1.25timesleft(dfrac{180^{circ}}{pi radians} right)=143.2^{circ}$
$x=dfrac{143.2^{circ}}{360^{circ}}(2pi)(65)$
$x=162.5$m
#### (c)
$150^{circ}=150^{circ}timesleft(dfrac{pi radians}{180^{circ}} right)=dfrac{5pi}{6} radians$
$x=dfrac{dfrac{5pi}{6}}{2pi}(2pi)(65)$
$x=dfrac{5}{12}(2pi)(65)$
$x=dfrac{325pi}{6} cm$
b) $x=162.5$m
c) $x=dfrac{325pi}{6} cm$
$angle BCA=dfrac{pi}{2}-dfrac{pi}{6}=dfrac{pi}{3}$
Because they are vertical angles,
$angle BCA=angle DCF, angle DCF=angle DCE+angle ECF$
$dfrac{pi}{3}=dfrac{pi}{12}+angle ECF$
$angle ECF=dfrac{pi}{3}-dfrac{pi}{12}$
$angle ECF=dfrac{pi}{4}$
Since $angle ECF=dfrac{pi}{4}$, $x=sqrt{2}(CE)=4.5sqrt{2}$ cm.
It rotates $4$ times per min. So it rotates once every $15$ seconds.
$omega=dfrac{2pi radians}{15 s}=0.418 88 radians/s$
#### (b)
Radius=$3$m
Revolutions, $n=(4 rev/min)(5 min)=20 rev$
distance travelled$=20(2pi)(3)=377.0$m
$omega=1.2pi rad/s(60 s/min)=72pi rad/min$
$72pi rad/minleft(dfrac{180^{circ}}{pi radians} right)=12 960^{circ}$
In one minute, the wheel rotates $12 960^{circ}$. So, Revolutions,
$n=12 960^{circ}div360^{circ}=36$
#### (b)
The wheel travels $(9.6pi)(6)=57.6pi$ metres in a minute.
$57.6pi=36(2pi)(r)$
$0.8m=r$
The angular velocity of piece $A$ is equal to piece $B$ because they rotate at same speed around the centre.
#### (b)
The velocity of piece $A$ is greater than piece $B$ because the radius od $A$ is greater than the radius of $B$.
#### (c)
The percentage would stay the same.
$30^{circ}=30^{circ}timesleft(dfrac{pi radians}{180^{circ}} right)=dfrac{pi}{6} radians;$
$45^${circ}$=45^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)= $dfrac{pi}$
{4} radians;$\$60^${circ}$=60^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)=$dfrac{pi}{3}$ radians;$\$90^${circ}$=90^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)=$dfrac{pi}{2}$ radians;$\$120^${circ}$=120^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)=$dfrac{2pi}{3}$ radians;$\$135^${circ}$=135^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)= $dfrac{3pi}{4}$ radians;$\$150^${circ}$=150^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)=$dfrac{5pi}{6}$ radians;$\$180^${circ}$=180^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)= pi radians;$\$210^${circ}$=210^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)= $dfrac{7pi}{6}$ radians;$\$225^${circ}$=225^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)=$dfrac{5pi}{4}$ radians;$\$240^${circ}$=240^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)= $dfrac{4pi}{3}$ radians;$\$270^${circ}$=270^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)=$dfrac{3pi}{2}$ radians;$\$300^${circ}$=300^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)= $dfrac{5pi}{3}$ radians;$\$315^${circ}$=315^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)= $dfrac{7pi}{4}$ radians;$\$330^${circ}$=330^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)= $dfrac{11pi}{6}$ radians;$\$360^${circ}$=360^${circ}$timesleft($dfrac{pi radians}{180^{circ}}$ right)= 2pi radians;$
Circle B: $dfrac{dfrac{pi}{7}}{2pi}(17)=7.62$ cm
Circle C: $dfrac{dfrac{pi}{5}}{2pi}(2pi)(14)=8.80$ cm
So, from smallest to largest, the order of the ares would be Circle B, Circle A, and Circle C.
$64pi cmtimesleft(dfrac{1 m}{100 cm} right)timesleft(dfrac{1 km}{1000 m} right)=0.000 64pi km$
Revolutions$=dfrac{675 km}{0.000 64 pi km}=1 054 687.5$
$6 hr 45 min=765 mintimesleft(dfrac{60 s}{1 min} right)=45 900 s$
Rev/sec$=dfrac{1 054 687.5 rev}{45 900 s}=23 rev/s$
$23 rev times 360^{circ}=8280^{circ} / s$
$8280^{circ} /s=8280^{circ}timesleft(dfrac{pi radians}{180^{circ}} right)=144.5$ radians/s