Question

Help Please! I seriously don't understand this. Thanks. Verify each identity.

2. sin(x+π)/cos(x+3π/2) = tan^2 x - sec^2 x

Answer 1

http://tutorial.math.lamar.edu/pdf/Trig_Cheat_Sheet.pdf

Answer 2

can you keep on explaining it, like I have the sheet with all the identities and pellet, I just seriously don't understand how to do them. Like I have 24 questions, and I've understood legit 5 @nincompoop

Answer 3

did you look at the cheat sheet link I provided?

Answer 4

yup, and I feels like I'm looking at Chinese. like honestly i just completely suck at trig, i had an a in pre-cal until this, and like my teacher sucks, and the book does not explain at all

Answer 5

books do explain, it is a matter of comprehension

Answer 6

look at the second page of the link

Answer 7

like no i teach myself everything from the book before a test and i ace it, cause im a self-learner and i seriously cannot focus in a class but this particular subject i just cant seem to teach myself

Answer 8

yes, i did and like i said. chinese. like i think you expand the numerator and the denominator with the Sum and Difference Formulas, but then im just lost

Answer 9

eliminate the cosine on the left hand side by multiplying both sides by it

Answer 10

express the right-hand side by sin and cos

Answer 11

i dont understand that at all...

Answer 12

what will the expansion of numerator and denominator achieve? your steps must have some purpose to what you're trying to achieve.

Answer 13

eh did you learn trigonometry in algebra lessons?

Answer 14

im trying to prove the identity

Answer 15

yeah we can prove the equation to be true

Answer 16

if you followed the two steps I provided then write here what you have. we will proceed with the rest of the steps

Answer 17

Left side of the equation:
sin (x + Pi) = -sin x ; and cos (x + 3Pi/2) = sin x
sin ( x + Pi)/cos (x + 3Pi/2) = -sin x/sin x = -1(1)
Right side:
tan^2x - 1/sin^2x = sin^2x/cos^2 x - 1/cos^2x = (sin^2 x - 1)/cos^2x =
= -(1 - sin^2x)/cos^2 x= -cos^2 x/cos^2x = -1 (2)
Finally, compare left side (1) to right side (2).

Answer 18

not really, i mean i took algebra in 7th grade so i dont even remember anything. i just dont understand how to apply what you're saying. can you like draw it so i can visually see it

Answer 19

Correction: line 5:
Right side: tan^2 x - 1/cos^2 x = sin^2 x/cos^2 x - 1/cos^2 x =...

Answer 20

wait, so for the left side shouldn't it like equal the right side and not -1 cause your like proving it to be true?

Answer 21

The left side equals the right side. This proves the identity.

Answer 22

oh, so i actually understood what you did @thu1935, but like im supposed to do it differently you see i actually attached the correct answer, cause my teacher told us the answers. but, thank you so much for your help anyway, you were a lot more helpful than the other person who answered.

Answer 23

I doubt that you learned anything, but good luck anyway