SI Derived Units

Name	Symbol	Quantity	Equivalents	SI base unit equivalents
becquerel	$Bq$	radioactivity	$\frac{1}{s}$	$s^{-1}$
coulomb	$C$	electric charge	$s \cdot A, F \cdot V$	$s \cdot A$
farad	$F$	electrical capacitance	$C / V, s / Ω$	${k g}^{-1} \cdot m^{-2} \cdot s^{4} \cdot A^{2}$
gray	Gy	absorbed dose of ionizing radiation	J/kg	m²s^-2
hertz	Hz	frequency	$\frac{1}{s}$	$s^{-1}$
joule	$J$	energy, work-done, heat	$m \cdot N, C \cdot V, W \cdot s$	$k g \cdot m^{2} \cdot s^{-2}$
katal	$kat$	catalytic activity	$mol / s$	$mol / s$
newton	N	force	$k g \cdot m / s^{2}$	$k g \cdot m \cdot s^{-2}$
ohm	Ω	electrical resistance	$V / A$	$k g \cdot m^{2} \cdot s^{-3} \cdot A^{-2}$
pascal	$Pa$	pressure, stress, youngs modulus	$N / m^{2}$	$k g \cdot m^{-1} \cdot s^{-2}$
radian	rad	angle	$m / m$	1
sievert	Sv	equivalent dose of ionizing radiation	J/kg	m²s^-2
tesla	T	magnetic flux density, magnetic field strength	Vs/m², Wb/m², N/(Am)	kgs^-2A^-1
volt	$V$	potential difference, electromotive force	$W / A, J / C$	$k g \cdot m^{2} \cdot s^{-3} \cdot A^{-1}$
watt	$W$	power, radiant flux	$J / s$ , $V \cdot A$	$k g \cdot m^{2} \cdot s^{-3}$
weber	$Wb$	magnetic flux	$J / A, T \cdot m^{2}, V \cdot s$	$k g \cdot m^{2} \cdot s^{-2} \cdot A^{-1}$

A fuller list of SI derived units can be found at en.wikipedia.org.

Angle and Measures of Angle

An angle formed by two rays meeting at the vertex of the angle

An angle is the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle. Angles formed by two rays lie in the plane that contains the two rays. Angles are also formed by the intersection of two planes. These are called dihedral angles. Two intersecting curves may also define an angle, which is the angle of the rays lying tangent to the respective curves at their point of intersection. Angle is also used to designate the measure of an angle or of a rotation. This measure is the ratio of the length of a circular arc to its radius. In the case of a geometric angle, the arc is centred at the vertex and delimited by the sides. In the case of a rotation, the arc is centred at the centre of the rotation and delimited by any other point and its image by the rotation. (scrapped from https://en.wikipedia.org/wiki/Angle) Further reading at skillsyouneed.com

A definition of Angle:

The arc length equation can be rearranged to make the angle, $θ$ , to be the subject:

θ = \frac{180 l}{π r}

Here the angle $θ$ is measured in degrees and the equation implies that the angle is proportional to the ratio $\frac{l}{r}$ which means we can write;

φ = \frac{l}{r}

Taking the constant of proportionality to be one and where $φ$ is the angle in radians.

Radians are not used in everyday life and, sometimes, within science, technology, engineering, and mathematics (STEM), radians have been found to be far more "natural" in STEM.

Angles measured in degrees and radians are related thus:
Radians vs Degrees

Conversion between some frequently used angles are:

Turn	θ / °	φ / radians
0	0	0
$\frac{1}{12}$	30	$\frac{π}{6}$
$\frac{1}{8}$	45	$\frac{π}{4}$
$\frac{1}{6}$	60	$\frac{π}{3}$
$\frac{1}{4}$	90	$\frac{π}{2}$
$\frac{1}{2}$	180	$π$
$\frac{3}{4}$	270	$\frac{3 π}{2}$
1	360	$2 π$