emath formulae

a

area of sector (degrees)

a/360 x pi r²

arc length (deg)

a/360 × 2 pi r

area of sector (rad)

½ r² theta

arc length (rad)

r theta

sector area (radians)

½ r² (theta - sin theta)

curved SA of cone

pi r l (L is slant height )

volume of sphere

⁴/₃ pi r³

SA of sphere

4 pi r²

sum of interior angles in a polygon

(n-2) x 180

sum of exterior angles in a polygon

360

1 interior angle (REGULAR polygon)

(n-2) x 180

/ n

1 exterior angle (REGULAR polygon)

360 / n

congruency tests

SSS

SAS

AAS
RHS

similarity tests

AA

all ratios of 3 pairs of corresponding sides are equal (SSS)

→ a₁ / a₂ = b₁ / b₂

_{Ratio of 2 pairs of corresponding sides are equal and equal included angles}

standard deviation

square root : (sum of each value of x squared / number of x values) — mean squared

magnitude (length) (vectors)

sq root: x² + y²