Algebra 2 - Chapter 13

Question 1

Law of Cosines

Answer 1

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

Question 2

Area of a triangle formulas (6)

Answer 2

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

Question 3

Law of Sines

Answer 3

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

Question 4

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

Answer 4

Sin A = opp / hyp = h / b

• Sin A = h / b

Question 5

Rules in law of sines with h (6)

Answer 5

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

Question 6

arc length formula

Answer 6

S  = rØ
Ø = s/r

Question 7

degree –> radian

Answer 7

multiply # of degrees by (pi radians / 180)

Question 8

radians –> degrees

Answer 8

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

Question 9

which answers are undefined (2)

Answer 9

tan 90 and tan 270

Question 10

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

Answer 10

r = √x^2 +y^2

Question 11

trig functions

Answer 11

sin Ø = y/r
cos Ø = x/r
tan Ø = y/x

Question 12

how to find coterminal angles

Answer 12

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

Question 13

negative and positive directions in clock rotations (2)

Answer 13

clockwise = negative

counter clockwise = positive

Question 14

30-60-90 triangle

Answer 14

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

Question 15

45-45-90 triangle

Answer 15

opposite of 45 = n

opposite of 90 = n√2