Things Flashcards

1
Q

Centre of mass of a semicircle

A

4r/3π

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Centre of mass of solid cone

A

1/4 h

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Centre of mass of hollow cone

A

1/3 h

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Centre of mass of a solid hemisphere

A

3/8 r

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Centre of mass of a hollow hemisphere

A

1/2 r

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Even function

A

f(x)=f(-x)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Odd function

A

f(-x)=-f(x)

I.e. rotational symmetry of 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

d/dx(tan x)

A

sec^2(x)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

d/dx(cosec x)

A

-cosec x cot x

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

d/dx(sec x)

A

sec x tan x

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

d/dx(cot x)

A

-cosec^2(x)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

S tan x dx

A

ln(sec x) + c

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

S cosec x dx

A

-ln(cosec x + cot x) + c

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

S sec x dx

A

ln(sec x + tan x) + c

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

S cot x dx

A

ln(sin x) + c

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

SinCos -+ identities

A
cos(π-α) = -cos(α)
cos(α-π) = -cos(α)
cos(-α) = cos(α)
sin(π-α) = sin(α)
sin(α-π) = -sin(α)
sin(-α) = -sin(α)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Double angle formulae

A

sin(2A)=2sinA cosA
cos(2A)=cos^2(A)-sin^2(A)
=2cos^2(A) - 1
=1 - 2sin^2(A)

18
Q

Half angle formulae

A

Use double angle formulae and replace A with θ/2

19
Q

PF denominator with linear factor

A

(ax+b) -> A/(ax+b)

20
Q

PF denominator with irreducible quadratic factors

A

(ax2 + bx + c) -> (Ax + B)/(ax2+bx+c)

21
Q

PF denominator with a repeated factor

A

(ax+b)^2 -> A/(ax+b) + B/(ax+b)^2

22
Q

PF improper

A

When degree of numerator is greater than or equal to degree of numerator, quotient is polynomial of order top - bottom
Order4/order3 -> Ax + B + other fractions from other rules

23
Q

Integration by parts

A

S uv’ = uv - S u’v

24
Q

Integrating odd powers of sinx and cosx

A

Split sin^3(x) into sinx and sin^2(x), then convert the latter into 1-cos^2(x). Expand brackets and separate integrals.

25
Integrating even powers of sinx and cosx
Use double angle formula of cos to turn them into cos(2x)
26
Even powers of secx and cosecx
Use tan sec and cot cosec identities and differentials. Split into sec^2(x)sec^2(x)
27
Odd powers of secx and cosecx
Write sec^(n-1)xsecx and then integrate by parts
28
Dividing polynomials
To divide say x2 + 4x - 5 by (x+3), Set it identically equivalent to (x+3)(ax+b)+r Where ax+b is the quotient and r is the remainder
29
Remainder theorem
When f(x) is divided by (αx-β) the remainder is f(β/α)
30
Special sums
``` Σr = n(n+1)/2 Σr^2 = n(n+1)(2n+1)/6 Σr^3 = n^2(n+1)^2/4 ```
31
Newton Raphson iteration
x(n+1) = xn - f(xn)/f’(xn) Limitations include a slow convergence speed when the tangent is shallow near the root, and the fact that some starting points fail to find the nearby root, and find other roots instead. A divide by zero error can occur, which causes the method to fail.
32
Binomial expansion
(1+x)^n=1+nx+n(n-1)/2!x^2… | Valid for |x|<1
33
Maclaurin expansion
f(x)=f(0) + f’(0)x + f’’(0)x^2/2! +…
34
How to determine if g(x) converges
If 1
35
Plotting a complex conjugate
Reflects in real axis
36
Modulus and argument of z^n
arg(z^n)=narg(z) | |z^n|=|z|^n
37
Modulus and argument of wz
|wz|=|w||z| | arg(wz)=arg(w)+arg(z)
38
Rotation with matrix
Clockwise (cosθ sinθ) (-sinθ cosθ)
39
Inverse matrix
1/(ad-bc) (d -b) | (-c a)
40
(AB)^-1
B^-1 * A^-1