數學的公式

Percentage change
Increase = new value - original value
Percentage increase = increase / original value x 100%
New value = original value x (1 + percentage increase)

Decrease = original value - new value
Percentage decrease = decrease / original value x 100%
New value = original value x (1 - percentage decrease)

Percentage change = (new value - original value) / original value x 100%

Profit and Loss
Profit = selling price - cost price
Profit % = profit / cost price x 100%
Profit = cost price x profit %
Selling price = cost price x (1 + profit %)

Loss = cost price - selling price
Loss % = loss / cost price x 100%
Loss = cost price x (1 - loss %)

Discount
Discount = marked price - selling price
Discount % = discount / marked price x 100%
Selling price = marked price x (1 - discount%)

Simple interest
I = PRT / 100
A = P + I = P (1 + RT / 100)


Euler's formula (a convex polyhedron)
F + V - E = 2


Total Surface Areas and Volumes of Prisms
Total surface area of a prism =
areas of the two bases + total area of all lateral faces
Volume of a prism = area of base x height


Angles Related to Intersecting Lines
∠s at a pt.
adj. ∠s on st. line
vert. opp. ∠s

Angles Formed by Parallel Lines and a Transversal
corr. ∠s, AB//CD
alt. ∠s, AB//CD
int. ∠s, AB//CD

Conditions for Two Lines to be Parallel
corr. ∠s equal
alt. ∠s equal
int. ∠s supp.


Conditions for Two Triangles to be Congruent
SSS
SAS
ASA
AAS
RHS

Condition for Two Triangles to be Similar
AAA
3 sides proportional
ratio of 2 sides, inc. ∠

中一級數學據我所知無公式,全是方程、指數記數法、方程縮寫的基本技巧+正負數和圖表