Using the Pythagorean trig identity | Trig identities and examples | Trigonometry | Khan Academy

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Trigonometry on Khan Academy: Big, fancy word, right? Don't be fooled. Looking at the prefix, tri-, you could probably assume that trigonometry ("trig" as it's sometimes called) has something to do with triangles. You would be right! Trig is the study of the properties of triangles. Why is it important? It's used in measuring precise distances, particularly in industries like satellite systems and sciences like astronomy. It's not only space, however. Trig is present in architecture and music, too. Now you may wonder...how is knowing the measurement and properties of triangles relevant to music?? THAT is a great question. Maybe you'll learn the answer from us in these tutorials!

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[nayelirojas]

I learned a lot more in 6 minutes than in my 1hr 15 class. Pretty useful, thanks !

[esme_melody]

Thank you so much! I'm understanding the hardest part of Algebra II because of your tutorials. :D

[RockmanR]

"The tangent is the slope of the angle". That's very interesting and helpful to know!

[mozartstudio]

Ever tried giving more examples in these and dumbing it down some? Especially with this section? Necause I feel just as lost, if not more so.

[courtneybalaban]

If theta is greater than -3π/2 (which is 270 deg), but less than π (which is 180 deg), why doesn't theta fall in quadrant 3? Why is it instead in quadrant 2?

[EagleLogic]

Well that was actually a really nice circle! Better than my unit "ovals" lol. When I did the problem myself I went the definition route instead of the identity route. Got the same answer, except positive.

[denaemendez]

This video was very helpful! My pre-calculus teacher was supposed to teach me this but didn't so now I have to teach myself this as I'm in calculus :/ but this video made things so much clearer! Thank you!

[christianbarrera]

These videos look so beautiful on an OLED panel

[wallec]

Sorry if it’s a stupid question but can this be done if you know the values for Sin Ø & Cos Ø?

[JetFeather]

Bruh i have a quiz in a few hours thank you man

[wattheshet]

Still confuse. Why is the sign of cosine negative?

[vishnuakundi]

can't you just use right triangles to visualize the information? In a sense, construct a right triangle in your head to find cos theta and ultimately tan theta? I understand that it is the same thing essentially, but I feel it is unnecessary.

[davont]

Sir aside from out black spot and like snake it answers not so more distraction while I am leaving such sad cases not to mathematicians who expand knowledge but to fellow shrinkers and supporting stinkers bless them and Pythagoras was right squares are duller.