Big Sheet
Wednesday, 24 August 2022 | |
6-minute read | |
1207 words | |
Geometry
Area
Area of equilateral triangle
$A = \frac{\sqrt{3}}{4} s^2$
Trapezoid
$A = h \cdot \frac{1}{2}(b_1 + b_2)$
Circles
\[ A = \pi r^2 \]
Semi-circle: $\frac{1}{2} A = \frac{1}{2} \pi r^2$
Triangles
Right
\[ A = \frac{1}{2}bh \]
Equilateral
\[ A = \frac{\sqrt{3}}{4} x^2 \]
Surface Area
Cylinder
$\textrm{SA} = 2\pi r^2 + 2\pi r h$
Sphere
$\textrm{SA} = 4\pi r^2$
Pythagorean Triples
- 3, 4, 5
- 5, 12, 13
- 7, 24, 25
- 8, 15, 17
Precalculus/Algebra
Trig ratios for special angles
\begin{array}{ r | c | c | c | c | c } f & 0 & \frac{\pi}{6} & \frac{\pi}{4} & \frac{\pi}{3} & \frac{\pi}{2} \\ \hline \sin & 0 & \frac{1}{2} & \frac{\sqrt{2}}{2} & \frac{\sqrt{3}}{2} & 1 \\ \cos & 1 & \frac{\sqrt{3}}{2} & \frac{\sqrt{2}}{2} & \frac{1}{2} & 0 \\ \tan & 0 & \frac{1}{\sqrt{3}} & 1 & \sqrt{3} & \textrm{undef} \\ \end{array}
Trig identities
\[ sin ^2 x + cos ^2 x = 1 \]
\[ 1 + \tan ^2 x = \sec ^2 x \]
\[ 1 + \cot ^2 x = csc ^2 x \]
Range of inverse trig functions
\begin{array}{ r | l } \sin^{-1} & [ -\frac{\pi}{2}, \frac{\pi}{2} ] \\ \cos^{-1} & [ 0, \pi ] \\ \tan^{-1} & ( -\frac{\pi}{2}, \frac{\pi}{2} ) \\ \csc^{-1} & [-\frac{\pi}{2}, 0) \cup (0, \frac{\pi}{2}] \\ \sec^{-1} & [0, \frac{\pi}{2}) \cup (\frac{\pi}{2}, \pi] \\ \cot^{-1} & (0, \pi) \\ \end{array}
Factoring patterns
\[ (a + b)^3 = a^3 + 3a^2b + 3ab^2 + b^3 \]
\[ a^2 - b^2 = (a + b)(a - b) \]
\[ a^3 + b^3 = (a + b)(a - b)^2 \]
\[ a^3 - b^3 = (a - b)(a + b)^2 \]
Log and exponent rules
\[ \log a + \log b = \log(ab) \]
\[ a\log b = \log(b^a) \]
Odd/Even Functions
The degree of the function determines if a function is odd/even. An odd function has an infinite range while an even function "mirrors" and has a limited range.
Calculus
Definition of a limit existing
A limit exists at a point when the function approaches a value at the point, whether or not the function exists at that point. When a left-hand and right-hand limit both exist at the same point, then a limit exists at that point.
Continuity at a point (define using limits)
A function is continuous when the limit exists (left-hand and right-hand) and $f(x)$ exists at that point.
\[ \lim_{x \to c} f(x) = f(c) \]
Continuity of an interval and function
An interval or function is continuous if the domain exists for all real numbers, and a limit exists at the x-value such that $x$ is any arbitrarily selected number.
A continuous function must be continuous at all points $(x, f(x))$ in its domain.
Discontinuity
- Jump discontinuity
- Infinite discontinuity
- Removable discontinuity
Derivative Rules
Sum rule: $(f(x) + g(x))' = f'(x) + g'(x)$
Product rule: $(f(x) \cdot g(x))' = f(x)g'(x) + f'(x)g(x)$
Quotient rule: $(\frac{f(x)}{g(x)})' = \frac{f'(x)g(x) - f(x)g'(x)}{g^2(x)}$
Reciprocal rule: $(\frac{1}{f(x)})' = -\frac{f'(x)}{f^2(x)}$
Chain rule: $(f(g(x)))' = f'(g(x)) \cdot g'(x)$
Derivatives of Exponentials/Logs
$\log_b'(a) = \frac{1}{a \ln b}$
$(b^a)' = b^a \ln b$
$\ln'(a) = \frac{1}{a}$
$(e^a)' = e^a$
Physics
Type | Derivative | Unit |
---|---|---|
Displacement | 0th | Distance |
Velocity | 1st | Distance over time |
Acceleration | 2nd | Distance over time over time |
Position
\[ s(t) \]
Instantaneous Velocity
\[ v(t) = s'(t) = \frac{ds}{dt} \]
Displacement
Over a time interval $[a, b]$
\[ \Delta s = s(b) - s(a) \]
\[ \int_a^b v(t) dt = s(b) - s(a) \]
Average Velocity
\[ \frac{\Delta s}{\Delta t} = \frac{1}{b - a} \int_a^b v(t) dt \]
\[ \frac{s(b) - s(a)}{b - a} = \frac{\Delta s}{\Delta t} \]
Speed
\[ \left| v(t) \right| \]
Total Distance Traveled
\[ \int_a^b \left| v(t) \right| dt \]
Average Acceleration
\[ \frac{\Delta v}{\Delta t} = \frac{1}{b - a} \int_a^b a(t) dt \]
Derivative of an inverse function
$(f^{-1})'(x) = \frac{1}{f'(f^{-1}(x))}$
Derivative of trig functions
\[ \sin(x)' = \cos(x) \]
\[ \cos(x)' = -\sin(x) \]
\[ \tan(x)' = \sec^2(x) \]
\[ \csc(x)' = -\cot x \csc x \]
\[ \sec(x)' = \sec x \tan x \]
\[ \cot(x)' = -\csc^2(x) \]
Derivatives of Inverse Trig Functions
$\arcsin'(x) = \frac{1}{\sqrt{1 - x^2}}$
$\arccos'(x) = -\frac{1}{\sqrt(1 - x^2)}$
$\arctan'(x) = \frac{1}{x^2 + 1}$
$(cot^{-1})'(x) = -\frac{1}{x^2 + 1}$
$(csc^{-1})'(x) = -\frac{1}{|x|\sqrt{x^2 - 1}}$
$(sec^{-1})'(x) = \frac{1}{|x|\sqrt{x^2 - 1}}$
Common Limits/Derivatives
\[ \lim_{x \to 0} \sin(\frac{a \sin x}{b}) = \frac{a}{b} \]
Fun Chart
\begin{array}{ c c c c } f(x) & \cup & \cap \\ f'(x) & \textrm{inc} & \textrm{dec} \\ f''(x) & + & - \end{array}
Super Fun Chart
\begin{array}{ c c c c } \int f(x) & \cup & \cap \\ f(x) & \textrm{inc} & \textrm{dec} \\ f'(x) & + & - \end{array}
Second Derivative Tests
$f'(c) < 0$ max
$f'(c) > 0$ min
Overestimation of Linear Approx.
A linear approx is an overestimate if $f(x)$ is concave down. A linear approx is an underestimate if $f(x)$ is concave up.
Integration Rules
\[ \int_{a}^{b} f(x) dx = - \int_{b}^{a} f(x) dx \]
\[ \int_{a}^{b} f(x) dx + \int_{b}^{c} f(x) dx = \int_{a}^{c} f(x) dx \]
Average rate of change of a function
\[ \frac{f(b) - f(a)}{b - a} \]
Average value of a function
\[ \frac{1}{b - a} \int_{a}^{b} f(x) dx \]
Average velocity
\[ \frac{s(b) - s(a)}{b - a} \]
MVT
Derivatives
If $f(x)$ is continuous on $[a, b]$ and differentiable on $(a, b)$ then there exists a value $c$ in $(a, b)$ such that $f'(c) = \frac{f(b) - f(a)}{b - a}$
Integrals
If $f(x)$ is continuous on $[a, b]$ then there exists a value $c$ in $[a, b]$ such that $f(c) = \frac{1}{b - a} \int_a^b f(x) dx$
FTC
If $f(x)$ is continuous on $[a, b]$, then $\frac{d}{dx} \int_a^x f(t)dt = f(x)$.
If $f(x)$ is continuous on $[a, b]$ and $F(x)$ is an antiderivative of $f(x)$, then $\int_a^b f(x) = F(b) - F(a)$
LRAM, RRAM, MRAM
If $f'(x) > 0$ for all $x$, then RRAM would be an overestimate, and LRAM would be an underestimate.
If $f'(x) < 0$ for all $x$, then RRAM would be an underestimate, and RRAM would be an overestimate.
Exponential Growth
\[ \frac{dy}{dt} = ky \Rightarrow y = y_0e^{kt} \]
where $y_0 = C$
$k < 0$ exp. decay
$k > 0$ exp. growth
Logistic Growth
\[ \frac{dy}{dt} = ky(L - y) \Rightarrow y = \frac{L}{1 + Ae^{-Lkt}} \]
\[ \lim_{t \to \infty} y = L \]
Point of inflection at $\frac{L}{2}$, where $y$ is growing the fastest
Disk
\[ A = \pi r^2 \]
\[ V = \pi \int (r(x))^2 dx \]
Washer
\[ A = \pi(R^2 - r^2) \]
\[ V = \pi \int (R(x)^2 - r(x)^2) dx \]
Arc Length
\[ L = \int_a^b \sqrt{1 + (\frac{dy}{dx})^2} dx \]
Depending on the problem, $\frac{dx}{dy}$ may be used instead.
Parametric
\[ \int_a^b = \sqrt{(\frac{dx}{dt})^2 + (\frac{dy}{dt})^2} \]
Parametric
\[ \frac{dy}{dx} = \frac{dy}{dt} \cdot \frac{dt}{dx} \]
\[ \frac{d^2y}{dx^2} = \frac{d}{dt} \frac{dy}{dx} \cdot \frac{dt}{dx} \]
Planar Motion
Position
\[ r(t) \langle x(t), y(t) \rangle \]
Velocity
\[ v(t) = r'(t) = \langle x'(t), y'(t) \rangle \]
Speed
\[ \left| v(t) \right| = \sqrt{x'(t)^2 + y'(t)^2} \]
Polar
\[ x = r cos \theta \]
\[ y = r sin \theta \]
\[ \frac{dy}{dx} = \frac{\frac{dy}{d \theta}}{\frac{dx}{d \theta}} \]