Pure Year 2 Flashcards
What is important to remember about sectors and small angle approximations?
Angles in radians NOT degrees
Shift
Setup
2
2
Arc length formula
r{theta}
theta must be in radians
Sector area formula
0.5r²{theta}
theta must be in radians
Area of a segment formula
(0.5r²{theta} - 0.5r²sin{theta}
theta must be in radians
When theta is small, 9{theta}²-2{theta}+1 is what?
1
theta is small so approximately 0, meaning that the first 2 terms become 0 so just leaves 1
What is a mapping?
Transforms one set of numbers into a different set of numbers
It is a function if every input has a distinct output
Is a one-to-one mapping a function?
Yes
Each input has one distinct output
Is a many-to-one mapping a function?
Yes
Each input has a distinct output
Is a one-to-many mapping a function?
No
Not every input has a distinct output
Is y=1/x a function
No
No value at 0, doesn’t map anywhere
Can be made a function by restricting domain to x≠0
Domain…
The set of X values for which the function is valid
Writen as x=a
Range…
The set of Y values that the function can take
Written as a<=f(x)<=b
How do you deal with partial fractions?
Multiply up
Knock out brackets by substituting values in to make some coefficients 0
What is a piecewise-defined funtion?
A function which consists of more than one part
When drawing:
●=less/more than or equal to
○=less/more than
What is an inverse function?
The mathematical opposite of the original function
Only exists for one-to-one functions
Y becomes X, X becomes Y, reflected in line Y=X
How do you get an inverse function?
Replace f(x) with y
Swap y and x
Rearrange to make x the subject
Swap y for f(x)
Check f(x) and not any other function notation e.g g(x)
When do inverse functions exist
One-to-one functions
What is the domain of an inverse?
The range of the ordinary function
What is the range of an inverse function?
The same as the domain of the normal function
If f(x)=sinx, the inverse function can be written as…
f-¹(x)=sin-¹x=arcsinx
Sketch the graph of y=arcsinx
State the range and domain
X Intercept: 0
Y Intercept: None
Coordinates: (-1,-90) (0,0) (1,90)
If f(x)=cosx, the inverse function can be written as…
f-¹(x)=cos-¹x=arccosx
if f(x)=tank, the inverse function can be written as…
f-¹(x)=tan-¹x=arctan
What is the modulus of a number?
It is the non negative numerical value
Also known as the absolute value
Denoted as |x|
What is the difference between y=f(|x|) and y=|f(x)|?
y=f(|x|) will not have a negative value input, meaning that negative values of x will become the positive values of x. The first quadrant is reflected in the y axis into the second quadrant and the fourth into third
y=|f(x)| will not go below the x axis since y cannot be negative. All negative in the third quadrant will reflect up into the second, and all negative in the fourth reflected up into the first
Sketch the graph of y=arccosx
State the domain and range
X intercept: 1
Y intercept: 90°
Key coordinates: (-1,180) (0,90) (1,180)
Asymptotes: ?
Reflected in the y=x axis
Sketch the graph of y=arctanx
State the range and domain
Online image
How do you access modulus feature on calculator?
Shift
Abs (absolute)
What’s important to remember once you have solutions for a modulus function?
Sub back in to check no phantom solutions (signs not equal once put back in on either side of equation)
How do you deal with solving modulus equations?
Draw the graphs look for intersections
Make modulus positive, solve, check for phantom solutions
Make modulus negative, solve, check for phantom solutions
What are reciprocate functions called?
Cosecant=Cosec
Secant=Sec
Cotangent=Cot
What is the rule to remember reciprocal functions?
Look at the third letter for each, will match what is on the bottom
Formula for Cosecant?
Cosec(x)=1/sin(x)
What is the formula for Secant?
Sec(x)=1/cos(x)
Formula for Cotangent?
Cot(x)=1/tan(x) OR cos(x)/sin(x)
Sketch the graph of y=cosec(x) in range (range two pie to negative two pie)
Image online
Sketch the graph of y=sec(x) in range negative two pi and two pi
Get an image online
Sketch the graph of y=cot(x) in the range negative two pi to two pi
Get an image from online
Method for solving equation involving reciprocal functions?
Change
Flip
Solve
Solve sec(x)=0
1/cos(x)=0
cos(x)=1/0
1/0 = no solutions
Solve cosec(x)=0
1/sin(x)=0
sin(x)=1/0
1/0 = no solutions
Solve cot(x)=0 in range 0° to 360°
1/tan(x)=0
tan(x)=1/0
1/0 = asymptotes, meaning 90°, 270°
2 trig functions from year 12
tan(x)=sin(x)/cos(x)
sin²(x)+cos²(x)=1
2 trig identities from year 13, derived from sin²(x)+cos²(x)=1
1+tan²(x)=sec²(x)
1 with a tan is sexy
1+cot²(x)=cosec²(x)
1 in a cot is cosy
How can you derive the two trig identities from sin²(x)+cos²(x)
Divide by cos
Divide by sin
Where do the addition formula appear?
Page 6 of formula booklet
Double angle formula for sin2x
2sinxcosx
Double angle formulas for cos2x
cos²x-sin²x
2cos²x-1
1-2sin²x
Double angle forumla for tan2x
2tanx
______
1-tan²x