Solving Trigonometric Equations Using the Quadratic Formula - Example 2

[fauxpas]

Thank you so much! far better than my teacher!

[bryceee]

Very helpful -- great video, thank you!

[rawsuperstar]

Thank you my friend this was very helpful 

[synunn]

cheers, this video just fixed a 2.5hour headache!

[arstgkneio]

If I have 2cos^2x can i say that it is interchangeable with 2(1-sin^2x)?

[Trust]

how did you do cos inverse of cos theta on your calculator?

[Skywalker]

Hi Patrick, can you give some examples of solving systems of trig equations
I need to find both x and y for
arcsin x arcsin y = pi^2/12
arccos x arccos y = pi^2/24
please help me out. If you didnt reply soon enough then probably means I failed the quiz, because i a quiz over it tomorrow, and my teacher haven't teach this yet.
however, i still with you can do some videos about this kind of problems, at least that would help other people and i will come back to learn this.

[mathdoris]

@jsm666 That is not why, H0SS302. The reason you can't say +/- 68.13 degrees is because the problem asked for the solutions ONLY between 0 and 2 pi. Although -68.13 is technically would work, it is not between 0 and 2 pi which the problem is requesting.

[srishtiarya]

Hey so by "distributing the negative" what did you mean? If you multiply the entire equation by -1 to make the cos^2theta into positive (because at the start it was 1-cos^2theta, hence negative and we can't work with that very well) then the entire quadratic is reversed :. 5costheta-1-cos^2theta=1 =>-5costheta+1+cos^2theta=1 OR cos^2theta-5costheta=0 (+1 and -1 cancel out) or am I really wrong? (i get that wrong a lot)

[quintinmagill]

how would i do an equation that goes like cos x (2 sin x - root3) = 0

[AA-lllu]

When u bring over the one why did it not change to -1 ?

[crabnebula]

I completely forgot about the quadratic equation lmao

[toastburntbread]

i'm crying because this is so easy, and I have spent two days trying to solve for theta without using the quadratic formula, for i thought you couldn't use it with trigonometric functions. :( I AM SO SAD.

[RocanMotor]

@kagomeh14cynthy lefties are annoying? what the hell gives you that notion?

And I'm a righty, before you think I'm defending lefties for personal reasons.