Solving Trigonometric Equations | A-level Mathematics

Solving trigonometric equations - from the basics to more challenging problems. This is a large topic but with practice and a good understanding of the fundamentals you can master it quickly.

*At 11:53 the interval should be for x, not theta

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00:00 intro
00:58 Level 1 equations
11:19 Level 2 equations
23:49 Level 3 equations

[denas]

this is the most clear and concise explanation of this topic i have found. Coming from someone who isnt doing great at this topic, this video is great, thanks😁

[mrmovie.]

Your explanation is straight to the point, I respect it.

[reimm]

srsly an amazing video everything is in it it

[NihonWoYumemite]

Thanks for showing the trickier problems! Massive help

[deplannest]

Thnkz you so much but the last eqn needs more explanations

[JPL]

Remember people, when you have two different trignometric relations on a equation just swap one of them with transformations

[ELLIPTICALWR]

does the t formulae work for when there is like a sin squared or cos squared in the equation., or like translation of sin/cos?

[ELLIPTICALWR]

the last one can be done by identifying it is a hidden cubic and can be solved using a polynomial solver or factor therom that way

[jfuqigz]

The last one was too much. However, it is a really helpful video

[hegel]

I have a question, answer would be very helpful. Why do we not have 6 answers in last exercise, isn't it that cosine has the same value for two different angles? Cos(20°) is the same as cos(340°) so why isn't 340° also one of the answers?

[qgiyttc]

I'm confused on the 4th question why were there 4 values I thought that with sin up to 360 would only have 2 values 57.69, 122.3

[marshalltakunda-cmxy]

Hi. How dd you get (2Cosx- 1)(Cosx-1) on level two

[novice]

9:23 The question was
(I'll use 0 as a representative of theta)
Solve the equation sin0 + cos0 = 0

You rearranged the formula so you got sin0/cos0 = -1
The completed the rearrangement by turning sin0/cos0 into tan0. So you ended up with
tan0 = -1

To get 0 on it's own you formed the formula 0 = tan-1 (-1)

I get all of that. What I don't get is why you used the sin equation (180 - x) instead of the tan equation (180 + x) to get the values, seeing as Tan is the only one there, and not sin.

Would the values not be:

x = [45] and [225]

[NNN]

16:19 shouldn't it be "-2cos^2θ + 3cosθ - 1 = 0"?

[assylbeksabyrzhan]

Why in the 2nd problem of level 2 equations didn't you simplify the term (1-cosA ) Because we can rewrite 2(1- (cosA)^2) as difference of squares and on right-hand-side we can get the same with 3(1-cosA) and then we will get only 1 solution. But how it is possible?

[toasteemi]

Wdym by A level we did this in Class 9

[daleflaherty]

How greedy have you been putting all these ads in. I'm not watching this as I refuse to watch 13 ads!

[Burningarrow]

I genuinely hate you for that last question. How tf do you expect your high school students to know how to solve that?