Algebra 2 - Chapter 13 Flashcards Preview

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Flashcards in Algebra 2 - Chapter 13 Deck (15):
1

Law of Cosines

a^2 = b^2 + c^2 - 2bc cos A
b^2 = a^2 + c^2 - 2ac cos B
c^2 = a^2 + b^2 - 2ab cos C

2

Area of a triangle formulas (6)

Area = 1/2bh
Area = 1/2bcSinA (reversible with different letters)

to find h:

Sin A = h/c or h = c(Sin A)

area = 1/2(bc)SinA
area = 1/2(ac)SinB
area = 1/2(ab)SinC

3

Law of Sines

sin A / a = Sin B / b = Sin C / c

4

in law of sines, what is the formula to find h

Sin A = opp / hyp = h / b

* Sin A = h / b

5

Rules in law of sines with h (6)

if h > a, then 0 traingles possible
if h = a, then 1 triangle is possible
if h < a, then 2 triangles are possible

- if 2 triangles exist, use law of sines to find angle B first
- There are 2 options for angle B but your calc only gives you one
~ to find the second B and C, subtract 180 from the other

6

arc length formula

S = rØ
Ø = s/r

7

degree --> radian

multiply # of degrees by (pi radians / 180)

8

radians --> degrees

multiply # of radians by (180 degrees / pi radians)

9

which answers are undefined (2)

tan 90 and tan 270

10

formula to find r on a grid (w/ trig functions of sin Ø = y/r)

r = √x^2 +y^2

11

trig functions

sin Ø = y/r
cos Ø = x/r
tan Ø = y/x

12

how to find coterminal angles

add 360 and then for the second angle, subtract 360 but make sure one of them is negative. *add 360 again if necessary

13

negative and positive directions in clock rotations (2)

clockwise = negative
counter clockwise = positive

14

30-60-90 triangle

opposite of 30 = n
opposite of 60 = n√3
opposite of 90 = 2n

15

45-45-90 triangle

opposite of 45 = n
opposite of 90 = n√2