# Search results

1. ### How do you prove this Trig identity?

I get ((sin^3(cos-sin)+cos^3(sin-cos))/((sin)((cos-sin)(cos)(sin-cos)) but somehow this doesn't seem right. How do I get a difference of squares?
2. ### How do you prove this Trig identity?

It's been a few days since first seeing this problem. I asked another math teacher, and he literally spent an entire class trying to solve it. My teacher has asked other teachers, and they haven't figured it out yet. I've worked the left side down to...
3. ### How do you prove this Trig identity?

Homework Statement (tan/(1-cot))+(cot/(1-tan))=1+(sec)(csc) The Attempt at a Solution This problem showed up in my class as a warm-up, and when my teacher tried to solve it for us he got stuck. I've asked a few classmates in higher level math, and they all seem to get stuck. I...
4. ### Finding the inverse of Sin

Alright, I think I can visuallize it now. Basically, I take 180-(first angle) and I should get my second angle. Thanks! P.S. Do I do the same thing for the other trig functions (cos, tan)?
5. ### Finding the inverse of Sin

Homework Statement This is from a physics problem, but my question is more mathematically oriented. After working through the problem, I arrive at the last step. Sin(x)=.967 The question says that there are two possible angles for x. The Attempt at a Solution arcsin(.967)...
6. ### (sec(x)+1)/tan(x) = (sin(x))/(1-cos(x))

Thank you very much! I would never have thought of multiplying by (1/cos) because it seemed so...random, yet it works. Do you have any tips on how to see things like that?
7. ### (sec(x)+1)/tan(x) = (sin(x))/(1-cos(x))

Homework Statement Prove. (sec(x)+1)/(tan(x))=(sin(x))/(1-cos(x)) Homework Equations Trig Identities The Attempt at a Solution I decided to try and prove the identity by manipulating the function on the right side. I multiplied both the numerator and denominator by...
8. ### Log(x)-log(x+4)=2 discrepancy

Thanks D H. But suppose that my teacher did defined the logarithm for all numbers both positive and negative. Is my answer then valid?
9. ### Log(x)-log(x+4)=2 discrepancy

Here are the wolframalpha results for the equation: http://www.wolframalpha.com/input/?i=log%28x%29-log%28x%2B4%29%3D2+solve+for+x&a=*FunClash.log-_*Log10.Log- Why does it give me a correct solution? Suppose the problem allowed for all possible answers (negative or possible) as long as...
10. ### Solve e^(2 x)-e^x-12 = 0 for x

I see your point. I've now talked to my teacher, and he thinks that I might be right; or at least he isn't sure why plugging in the solutions back into the equations work. If we are talking about logarithms that are defined by both positive and negative numbers (let's just say the problem...
11. ### Log(x)-log(x+4)=2 discrepancy

Why must I exclude the "impossible equations" if they work? Can you please define impossible (graphically? algebraically) Thanks
12. ### Log(x)-log(x+4)=2 discrepancy

Homework Statement log(x)-log(x+4)=2 Homework Equations knowledge of logs The Attempt at a Solution This question was on a test, and I found the answer to be approximately -400/99. I was marked off, because apparently the answer is no solution? I checked wolframalpha, and they...
13. ### Solve e^(2 x)-e^x-12 = 0 for x

Homework Statement solve e^(2 x)-e^x-12 = 0 for x Homework Equations quadratic The Attempt at a Solution We had this question on a test, and after solving it (i'd rather not write out the work), I came to two solutions. Ln(4) Ln(-3) I plugged both answers back into the...
14. ### E^x+x = 5

Homework Statement e^x+x=5 Homework Equations Lambert W-function? The Attempt at a Solution I moved everything around and got: Ln(5-x)=5.... It doesn't really help. I looked at wolframalpha, and it said I need the Lambert W-function (no clue what that is). Can this...
15. ### V^2 − (v/4)^2 = 196

I forgot to square the (1/4)! how silly of me. Thank you!
16. ### V^2 − (v/4)^2 = 196

Homework Statement I'm solving for v in: v^2 − (v/4)^2 = 196 Homework Equations The Attempt at a Solution →v^2(1-(1/4))=196 →v^2(.75)=196 → √(196/.75)≈16.17 What did I do wrong? I know this isn't the right answer, but why?
17. ### 3^x = 12x-9

I am assuming that it is, in fact, impossible to solve algebraically? I really don't see how moving everything around gets me closer to an answer. Thanks for trying though, mjordan2nd, unless there really is a way to solve it by taking your route. Please feel free to give me a few more hints...
18. ### 3^x = 12x-9

thanks guys for the help, sorry about asking for the step by step, I'm new here. as for the Lambert w-function, is it something one learns in Calculus or something? I'm only in precalculus.
19. ### 3^x = 12x-9

Homework Statement 3^x=12x-9 Homework Equations The Attempt at a Solution I really have no clue how to solve this one algebraically. I graphed the two functions on a calculator and found the points of intersection the answers are 3 and 1 Can someone show me how to solve...