Question

How do you solve cos(theta)+1=0

Answer 1

cos(theta)+1=0

cos(theta)+1-1=0-1

cos(theta) = -1

Now use the unit circle to find all values of theta that make cos(theta) = -1 true

Answer 2

Well im confused on the part of the unit circle and how to find the answer?

Answer 3

do you have the unit circle with you

Answer 4

Yes

Answer 5

ok the x coordinate of any point represents the cosine of the angle

for instance, at the point (1,0), the angle here is theta = 0

so this means

cos(theta) = cos(0) = 1

sin(theta) = sin(0) = 0

Answer 6

another point:

at (0,1), theta is 90 degrees, which means

cos(theta) = cos(90) = 0
sin(theta) = sin(90) = 1

Answer 7

see how I'm getting these?

Answer 8

So would the answer be 180

Answer 9

good, and if you're restricting theta to be an angle between 0 and 360, then that's the only solution

Answer 10

otherwise, it is

theta = 180 + 360*n

where n is any integer

Answer 11

Okay thank you so im doing summer homework and would inwrite the answer like: cos(theta)+1=180

Answer 12

no your answer needs to have theta isolated

Answer 13

because that's exactly what it means to solve for a variable

Answer 14

Ok so theta=180

Answer 15

you're looking for values of theta that make cos(theta)+1=0 true

if theta is between 0 and 360, then the only answer is theta = 180

if theta is not restricted, then the answers are theta = 180, theta = 540, theta = 900, etc etc

Answer 16

Ok thank you! Also for tan^2(theta)-5=0 what wouldbyou do with the squared

Answer 17

you would take the square root of both sides

but this is after you add 5 to both sides

Answer 18

So wouldmit look like this: theta= square root of 5

Answer 19

if x^2 = 4, then x = 2 or x = -2

notice how both solutions work

Answer 20

Yes sorry i accidentally closed the question

Answer 21

when x = 2

x^2 = 2^2 = 4

and

when x = -2,

x^2 = (-2)^2 = 4

so that explains the plus/minus when dealing with square roots