Find an angle
$\text{\hspace{0.17em}}\alpha \text{\hspace{0.17em}}$ that is coterminal with an angle measuring 870°, where
$\mathrm{0\xb0}\le \alpha <\mathrm{360\xb0}.$
$\alpha =150\xb0$
Given an angle with measure less than 0°, find a coterminal angle having a measure between 0° and 360°.
Add 360° to the given angle.
If the result is still less than 0°, add 360° again until the result is between 0° and 360°.
The resulting angle is coterminal with the original angle.
Finding an angle coterminal with an angle measuring less than 0°
Show the angle with measure −45° on a circle and find a positive coterminal angle
$\alpha $ such that 0° ≤
α <360°.
Since 45° is half of 90°, we can start at the positive horizontal axis and measure clockwise half of a 90° angle.
Because we can find coterminal angles by adding or subtracting a full rotation of 360°, we can find a positive coterminal angle here by adding 360°:
We can then show the angle on a circle, as in
[link] .
Find an angle
$\text{\hspace{0.17em}}\beta \text{\hspace{0.17em}}$ that is coterminal with an angle measuring −300° such that
$\text{\hspace{0.17em}}\mathrm{0\xb0}\le \beta <\mathrm{360\xb0}.\text{\hspace{0.17em}}$
$\beta =60\xb0\text{\hspace{0.17em}}$
Finding coterminal angles measured in radians
We can find
coterminal angles measured in radians in much the same way as we have found them using degrees. In both cases, we find coterminal angles by adding or subtracting one or more full rotations.
Given an angle greater than$\text{\hspace{0.17em}}2\pi ,$find a coterminal angle between 0 and$\text{\hspace{0.17em}}2\pi .$
Subtract
$\text{\hspace{0.17em}}2\pi \text{\hspace{0.17em}}$ from the given angle.
If the result is still greater than
$\text{\hspace{0.17em}}2\pi ,$ subtract
$\text{\hspace{0.17em}}2\pi \text{\hspace{0.17em}}$ again until the result is between
$\text{\hspace{0.17em}}0\text{\hspace{0.17em}}$ and
$\text{\hspace{0.17em}}2\pi .\text{\hspace{0.17em}}$
The resulting angle is coterminal with the original angle.
Finding coterminal angles using radians
Find an angle
$\text{\hspace{0.17em}}\beta \text{\hspace{0.17em}}$ that is coterminal with
$\text{\hspace{0.17em}}\frac{19\pi}{4},$ where
$\text{\hspace{0.17em}}0\le \beta <2\pi .$
When working in degrees, we found coterminal angles by adding or subtracting 360 degrees, a full rotation. Likewise, in radians, we can find coterminal angles by adding or subtracting full rotations of
$\text{\hspace{0.17em}}2\pi \text{\hspace{0.17em}}$ radians:
The angle
$\text{\hspace{0.17em}}\frac{11\pi}{4}\text{\hspace{0.17em}}$ is coterminal, but not less than
$\text{\hspace{0.17em}}2\pi ,$ so we subtract another rotation:
The angle
$\text{\hspace{0.17em}}\frac{3\pi}{4}\text{\hspace{0.17em}}$ is coterminal with
$\text{\hspace{0.17em}}\frac{19\pi}{4},$ as shown in
[link] .
Find an angle of measure
$\text{\hspace{0.17em}}\theta \text{\hspace{0.17em}}$ that is coterminal with an angle of measure
$\text{\hspace{0.17em}}-\frac{17\pi}{6}\text{\hspace{0.17em}}$ where
$\text{\hspace{0.17em}}0\le \theta <2\pi .$
Recall that the
radian measure$\text{\hspace{0.17em}}\theta \text{\hspace{0.17em}}$ of an angle was defined as the ratio of the
arc length$\text{\hspace{0.17em}}s\text{\hspace{0.17em}}$ of a circular arc to the radius
$\text{\hspace{0.17em}}r\text{\hspace{0.17em}}$ of the circle,
$\text{\hspace{0.17em}}\theta =\frac{s}{r}.\text{\hspace{0.17em}}$ From this relationship, we can find arc length along a circle, given an angle.
Arc length on a circle
In a circle of radius
r , the length of an arc
$\text{\hspace{0.17em}}s\text{\hspace{0.17em}}$ subtended by an angle with measure
$\text{\hspace{0.17em}}\theta \text{\hspace{0.17em}}$ in radians, shown in
[link] , is
Given a circle of radius$r,$calculate the length$s$of the arc subtended by a given angle of measure$\theta .$
If necessary, convert
$\text{\hspace{0.17em}}\theta \text{\hspace{0.17em}}$ to radians.
Multiply the radius
$\text{\hspace{0.17em}}r\text{\hspace{0.17em}}$ by the radian measure of
$\text{\hspace{0.17em}}\theta :s=r\theta .\text{\hspace{0.17em}}$
Finding the length of an arc
Assume the orbit of Mercury around the sun is a perfect circle. Mercury is approximately 36 million miles from the sun.
In one Earth day, Mercury completes 0.0114 of its total revolution. How many miles does it travel in one day?
Use your answer from part (a) to determine the radian measure for Mercury’s movement in one Earth day.
Let’s begin by finding the circumference of Mercury’s orbit.
In this morden time nanotechnology used in many field .
1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc
2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc
3- Atomobile -MEMS, Coating on car etc.
and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change .
maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.