Mathematical things Flashcards
Area of a circle formula…
A = pi (radius squared)
- If semi-circle, divide by 2
- If quarter of circle, divide by 4
Area of a sector formula…
- pi (radius squared) / 360 x theta
- OR pi (radius squared) x theta / 360
(Watch vids on this)
Arc length formula…
- pi (diameter) / 360 x theta
Area of a trapezium formula…
(a+b) x h / 2
Area of a triangle formulas…
- 1/2 x b x h
- 1/2 (a)(b)sin(C) -> use this when there’s an angle between two side lengths
Density formula…
density = mass / volume
(Convert units when required and use units properly)
Area of a square…
b x h
Missing sides for right angled triangles (when there’s two sides)…
Pythagoras (a2 + b2 = c2)
Missing angles for right-angled triangles…
-> SOH CAH TOA e.g. sine = opp/hyp -> then inverse both sides for finding angle
Missing sides or angles for non-right angled triangles…
-> Cosine rule -> a2 = b2 + c2 - 2(b)(c)Cos(A) | USE THIS for two sides and an angle adjacent to a side OR three sides
-> Sine rule so a / sinA, b / sinB c /sin C , sinA / a, sinB / b and sinC / c -> USE THIS for two sides and one angle opposite to side OR two angles and one side opposite to angle
(Equation rearrangment may be required)
Missing sides for right-angled triangle when there is just one side (with the angle)
- SOHCAHTOA
USE THIS for two sides and an angle adjacent to a side OR three sides…
(Missing sides or angles for NON-RIGHT ANGLED TRIANGLES)
Cosine rule -> a2 = b2 + c2 - 2(b)(c)Cos(A)
cosA = b2 + c2 - a2 / 2(b)(c)
cosB = a2 + c2 - b2 / 2(a)(c)
cosC = a2 + b2 - c2 / 2(a)(b)
(Labels could be all over…)
USE THIS for two sides and one angle opposite to any of two sides OR two angles and one side opposite to angle…
(Missing sides or angles for NON-RIGHT ANGLED TRIANGLES)
Sine rule so a / sinA, b / sinB c /sin C , sinA / a, sinB / b and sinC / c
Cylinder volume…
- pi x radius squared x h
