Maths Flashcards
Mutually exclusive events
P(A or B) = P(A) + P(B)
Non mutually exclusive events
P(A or B) = P(A) + P(B) - P(A and B)
Independent events
P(A and B) = P(A) * P(B)
Disadvantage of using the mean
Influenced by extreme values so may give a false view
Median disadvantage
Can only be used if ordered by size
Range
Heavily influenced by extreme values
Interquartile range
Not affected by extreme values but does not give a complete picture of the range
Plan
View from above looking down onto the object
Co-interior angles
Add up to 180
Area of a trapezium
0.5h(a+b)
If shape x is enlarged with scale factor n to give a similar figure
Area of similar figure is n^2 times area of x
Volume of similar figure is n^3 times area of x
Sin 30
= cos 60 = 1/2
Sin 60 =
Cos 30 = root(3)/2
Tan 30 =
1/root(3)
Tan 60
Root 3
Sin 45
= cos 45 = 1/root2
Tan 45 =
1
Sum of interior angles in n sided polygon
180 (n-2)
Sum of exterior angles in polygon
360
Diagonals on a kite and rhombus
Intersect at right angles
Kite
Pair of opposite angles which are equal
Congruent if
SSS
SAS (angle between them)
ASA
RHS (right angle hypotenuse side)
Invariant point
Centre of rotation ; unless angle of rotation is 0 or a multiple of 360, all points are invariant
Circle theorems
Angle at centre of a circle is twice the angle subtended at the circumference by the same chord
Angle in a semicircle is 90 degrees
Angles in the same SEGMENT (not sector) are equal
Angle between radius and tangent is 90 degrees
Alternate segment - angle between tangent and chord is = angle subtended by that chord
Opposite angles in a cyclic quadrilateral add up to 180
