Trick for doing trigonometry mentally!

This fast math trick can be used to mentally work out the main basic trigonometric ratios instantly! With this fast mental math technique you can work out the sin, the cos, and even the tan of the most common angles in no time at all! Become the trigonometry master!

[juliusnepos]

This guy is literally saving millions of people’s future by being better at math

[bootgrip]

29 year old civil engineering student... never heard of this. This is gold.

[Unknown-uqnc]

6 hours till my final, YouTube works in a mysterious ways

[kltcbp]

I cried from stressing myself trying to study this for my quiz tomorrow morning, found this video & now I just wanna give you a hug for helping me out. Thank you so much for this video! Keep up the good work!

[MonkeyGoatLicker]

I know a trick my friend made up. If you are trying to fill in a unit circle for degrees, than say, "30, 15, 15, 30, 30, 15, 15, 30." Until you are done filling it out. It would look like this on the circle: 30, 45, 60, 90, 120, 135, 150, 180, 210, 225, 240, 270, 300, 315, 330, 360. Keep adding 30 then 15 then 15 then 30 until you get to the end. Hope this helps.

[manupasquette]

Anyone else look this up for yr11 revision?

[thepro]

“I’m not the greatest artist” every Four year old disagrees

[dhy]

So, the Tangent would be the number of fingers on the right of the degree divided by the number of fingers on the left of the degree, and then the square root of that, i.e., the TAN of 60 would be sqrt (3/1); the TAN of 45 would be sqrt (2/2); the TAN of 30 would be sqrt (1/3).

[nazninsultana]

What kind of sorcery is this!!! Where were you my whole life?

[peterbohus]

Amazing! I know them perfectly for my exam tomorrow! Thank you so so much

[R_dacted]

This saves me so much time.... I always draw out two triangles and solve it that way. Nice trick!

[NoActuallyGo-KCUF-Yourself]

I think it would make more sense to number the fingers 0, 1, 2, 3, 4 - clockwise for cosine, counterclockwise for sine.

Then, just take the square root of that number over 2.

[nigglebit]

Your channel deserves more respect. Thanks for this.

[smahane]

what if I don't have 5 fingers :)

[anjumshabana]

It's a great trick, I'll improve it a bit before explaining to my students .Thanks for giving the idea.

[gwensimmons_gigi]

Yes like the left hand trick for Sine. Love this one also, but it’s more like the 9 times multiplication table trick which uses both hands. Math rocks!! Tfs! 😘✨👍🏾

[ivymayer]

This is pure gold, I can’t thank you enough 🙌🏼

[erickerick]

There are several ways to make things easier. You could remember the Sin() values in order from Sin(0) to Sin(90) as sqrt(x/4) with x varied from 0 to 4, then the Cos() would be the same values but invert their order. Afterwards Tan() is just solving Sin()/Cos().

Another way is to visualize rows for Sin() and Cos(), Sin() on top, with 30, 45 and 60 degrees as columns, then fill it left to right starting from top left "1, 2, 3, 3, 2, 1 ", divide everything by 2 and the numerators get a sqrt except for the ones with 1. You won't get values for 0 or 90 degrees but those are easy if you understand what Sin() and Cos() are on the trig circle.

[solerest]

Thank you! This makes my pre-calculus final tomorrow moderately less stressful! :D

[Mthnet]

Excellent. Simple way.
Very inspiring. Thank you.