CHAPTER 21 KEY FORMULAS AND EQUATIONS

Distance formula

Fig. 21.2

d = (x2 − x1)2 + (y2 − y1)2
(21.1)

Slope

Fig. 21.4

m = y2 − y1x2 − x1
(21.2)

Fig. 21.7

m = tan α(0 °  ≤ α < 180 ° )
(21.3)

Fig. 21.9

m1 = m2(for | | lines)
(21.4)

Fig. 21.10

m2 =  − 1m1or m1m2 =  − 1(for   ⊥ lines)
(21.5)

Straight line

Fig. 21.15

y − y1 = m(x − x1)
(21.6)

Fig. 21.18

x = a
(21.7)

Fig. 21.19

y = b
(21.8)

Fig. 21.22

y = mx + b
(21.9)
Ax + By + C = 0
(21.10)

Circle

Fig. 21.30
(x − h)2 + (y − k)2 = r2
(21.11)

Fig. 21.33

x2 + y2 = r2
(21.12)
x2 + y2 + Dx + Ey + F = 0
(21.14)

Parabola

Fig. 21.43
y2 = 4px
(21.15)

Fig. 21.46

x2 = 4py
(21.16)

Ellipse

Fig. 21.58
x2a2 + y2b2 = 1
(21.17)

Fig. 21.58

a2 = b2 + c2
(21.18)

Fig. 21.59

y2a2 + x2b2 = 1
(21.19)

Hyperbola

Fig. 21.71
x2a2 − y2b2 = 1
(21.20)

Fig. 21.71

c2 = a2 + b2
(21.21)

Fig. 21.70

y =  ± bxa(asymptotes)
(21.23)

Fig. 21.72

y2a2 − x2b2 = 1
(21.24)

Fig. 21.78

xy = c
(21.25)

Translation of axes

Fig. 21.83
x = x ′  + hand y = y ′  + k
(21.26)
x ′  = x − hand y ′  = y − k
(21.27)

Parabola, vertex (h, k)

(y − k)2 = 4p(x − h)(axis parallel to x-axis)
(21.28)
(x − h)2 = 4p(y − k)(axis parallel to y- axis)
(21.29)

Ellipse, center (h, k)

(x − h)2a2 + (y − k)2b2 = 1(major axis parallel to x-axis)
(21.30)
(y − k)2a2 + (x − h)2b2 = 1(major axis parallel to y-axis)
(21.31)

Hyperbola, center (h, k)

(x − h)2a2 − (y − k)2b2 = 1(transverse axis parallel to x-axis)
(21.32)
(y − k)2a2 − (x − h)2b2 = 1(transverse axis parallel to y-axis)
(21.33)

Second-degree equation

Ax2 + Bxy + Cy2 + Dx + Ey + F = 0
(21.34)

Rotation of axes

Fig. 21.97
x = x ′  cos θ − y ′  sin θy = x ′  sin θ + y ′  cos θ

Angle of rotation

tan 2θ = BA − C(A ≠ C)
(21.39)
θ = 45 ° (A = C)
(21.40)

Polar coordinates

Fig. 21.106
x = r cos θ = r sin θ
(21.41)
tan θ = yxr = x2 + y2
(21.42)
..................Content has been hidden....................

You can't read the all page of ebook, please click here login for view all page.
Reset
3.138.33.87