Key Maths Flashcards
What’s an equivalent fraction?
Fractions that look different but are equal to each other
How do you make an equivalent fraction
You times/divide the numerator and denominator by the same number
What’s an integer
A whole number
How do you add fractions?
Get common denominator then add numerators, then convert back to mixed. Subtracting is the same
How do you work out a fraction of an amount?
Divide by the denominator then times by the numerator
‘4/7 of 81’ what does the of mean?
4/7 x 81
What’s the rule for angles on a straight line?
Add up to 180*
What’s the rule for angles around a point?
Add up to 360*
What’s the rule for vertically opposite angles?
They’re equal
What’s the rule for angles in a triangle?
Add up to 180*
What’s an isosceles triangle?
Has two equal sides (lengths) and two equal base angles
What’s a quadrilateral?
Shape with 4 sides
What’s the rule for angles in a quadrilateral?
Add up to 360*
What’s the rule for alternative angles? What do these angles look like?
Are equal
Look for the S shape. As long as arms of S are parallel, angles in the S are equal
What’s the rule for corresponding angles? What do these angles look like?
Are equal
Look for the F shape, if arms of F are parallel then angles in the arm of F are equal
What’s the rule for co interior angles? What do these angles look like?
Add up to 180*
Look for C shape, if arms of c are parallel angles in the C add up to 180*
What does it mean for a shape to be Regular?
All sides are the same shape and all angles are the same size
What’s a quick way to work out how many triangles are in a regular shape?
Number of sides - 2
What’s the equation for the sum of the interior angles of any polygon?
(Number of sides - 2) x 180*
What’s a polygon?
A shape with at least three straight sides and angles
What do an exterior angle + an interior angle add up to?
180*
What do the exterior angles of a polygon add up to?
360*
What do a tangent and radius meet to make?
90*
Tangents from an extended point to a circle are what?
Equal in length
whats the circle theorem for when there’s an angle in the centre and the other three angles are touching the circumference of the circle?
Angle at centre is twice the angle of circumference
When does the circle Theorem ‘Angle at centre is twice the angle of circumference ‘ apply?
when there’s an angle in the centre and the other three angles are touching the circumference of the circle
What’s the circle theorem when all points of a ‘bow tie’ shape are touching the circumference?
Angles in the same segment are equal
What’s the circle theorem when one length of triangle is going through centre of circle, all vertices are touching circumference
The angle in a semicircle is always 90*
What’s the circle theorem for a cyclic quadrilateral
Opposite angles in a Cyclic quadrilateral add up to 180*
When is a quadrilateral cyclic?
All points of quadrilateral must be touching the circumference of a circle
What are the 2 rules for bearings?
Bearings are always measured clockwise from North, must always have 3 digits
How do you work out the HCF from a Venn diagram?
Multiply numbers in the middle
How do you work out the LCM using a Venn diagram?
Multiply all numbers in diagram together
A^m x a^n = ?
A^m x a^n = a ^m+n
A^m / a^n = ?
A^m / a^n = a ^m-n
(A^m)^n = ?
(A^m)^n = a^mxn
A^0 = ?
A^0 = 1
A^1/m = ?
A^1/m = m(square root of a)
A ^ n/m = ?
A^n/m = m(square root of a^n)
A^-n = ?
A^-n = 1/(a^n)
What does it mean when the question asks you to ‘evaluate’?
Work out
When dividing decimals using bus stop, which numbers need to be integers?
The number inside the busstop
When multiplying numbers in standard form what do you do?
Times the first integers, add the indices. Give answer in standard form
What are terms separated by?
Plus and minus signs
What are like terms?
Terms with the same letter
How do you expand triple brackets?
Expand first 2 brackets, then simplify answer, then expand with last bracket
How do you do simple factorising?
Look for HCF, rewrite but take HCF outside brackets
When do u use smiley face method to factorise?
When quadratic has number in front of x^2
What is the difference of two squares rule?
A^2-b^2 = (a-b)(a+b)
What’s a surd?
A square root of an integer that doesn’t give you an integer answer, eg square root of 5
What’s the surd law?
Square root of ab = square root of a square root of b
What does rationalising the denominator mean?
To get rid of the surd on the denominator
What’s the first significant figure of a number?
The first non zero figure reading from the left
How do you estimate?
Round each number to 1sf. Then work out the new calculation
How do you convert from a percentage to a decimal?
Divide by 100
How do you convert from a percentage to a fraction?
Write it over 100
How do you convert from a decimal to a percentage?
Times by 100
How do you convert from a decimal to a fraction
Multiply by 100 and write over 100
How do you convert from a fraction to a decimal?
Divide denominator by numerator OR try writing it over 100
How do you convert from a fraction to a percentage
Write over 100 OR change to decimal and x 100
What’s equation for speed?
Speed = distance / time
What’s equation for density?
Density = mass / volume
What is equation for pressure? What’s it usually measured in?
Pressure = force / area
N/m^2 or N/cm^2
1 m^2 = ? Cm^2
1m^2 = 100^2 cm^2 = 10000 cm^2
1 m^3 = ? Cm^3
1m^3 = 100^3 cm^3 = 1,000,000 cm^3
What’s an expression?
Has no equal sign
How do you solve fractional equations?
Make a common denominator, times by it, expand brackets, solve
What do you do to solve a quadratic equation that equals 0
Factorise. Has 2 answers (usually opposite of numbers made when factorising)
How do you solve a quadratic?
Make it equal 0
When factorising a quadratic,which number do the numbers in brackets want to add to make?
The one with an unknown
What do you use to solve simultaneous equations?
Substitution
What is the equation for a straight line?
Y = mx + c
C = y intercept, where it crosses y axis M = the gradient
What’s the rule for the gradient of parallel lines?
Parallel lines have the same gradient
What’s the rule for the gradient of perpendicular lines?
If you know the gradient of a line, the gradient of the line perpendicular to it will be the negative reciprocal of the first lines gradient
What are perpendicular lines?
Lines which cross each other at right angles
What’s the equation for the gradient of a line?
Change in y / change in x
What’s the equation for the midpoint of two coordinates
( [x1 + x2]/2 , [y1+y2]/2)
What’s the equation of Pythagoras theorem?
What are the three rules for when Pythagoras theorem?
a^2 + b^2 = c^2
Only works on right angled triangles
Hypotenuse = c, it is opposite the right angle
a and b can be any line
What are the five rules for trigonometry?
Only work o night angled triangles
Hypotenuse is the length opposite right angle
Theta is an angle in the triangle which isn’t the right angle
Opposite is the length opposite theta
Adjacent is the side adjacent to theta, but not the hypotenuse
What are the three trigonometry equations?
Sin theta = opposite / hypotenuse
Cos theta = adjacent / hypotenuse
Tan theta = opposite / hypotenuse
How do you enter 10xsin60=x into the calculator
Sin (60) x 10
When you have cos theta = number/number, how do you get the theta on its own?
Cos -1, giving theta = cos^-1 (6/12)