Basic Trigonometry Review

A review of basic trigonometry: Sine, Cosine & Tangent including how to use the ratios to find missing sides and missing angles on right triangles.

Category:

Howto & Style

Tags:

• trigonometry

[Sduibek]

This would be better without the massive sibilance :(

[mrjohaneson]

@Sduibek Thanks for the comment. I think you worded it wrong, though. I'm pretty sure what you meant to type was, "Hey, thanks for helping me with my trigonometry :)" And then I would say... you're welcome.

[pinoyoutoob]

how do you solve this? only the angle and opposite are given

[mrjohaneson]

@pinoyoutoob Remember that these are all RIGHT triangles, so you have one angle of 90° plus the angle given in the question. Subtract those from 180° to get the third angle. If you were given the opposite side, choose which other side to find first. If you choose the hypotenuse, then you'll use SIN. If you choose to find the adjacent, then use TAN. If you need both, do them one at a time using SIN & then TAN or find one and then use pythagoras' theorem for the third side.

[lltjekmeoutll]

how do you use a side and angle to get a side or another angle?

[mrjohaneson]

If you already know two sides, you can use Pythagoras' Theorem to find the third side (a squared plus b squared = c squared). If you know two angles and need to find the third angle, it's even easier since the three angles in a triangle always add up to 180°. Just do 180° minus the angle they gave you and minus the 90° angle in every right triangle. Whatever's left is the missing angle. Hope this helps.

[cristy02]

thank you sooooooooo much this was so helpful to me remembering this for my college placement exam!!!!!

[QuadCore120]

Thanks! Reviewing them refreshes my mind!

[kuhataparunks]

@mrjohaneson wow i wasn't thinking when i said radian lmao.... i really meant degrees :( i fewel stupid haha! :P but many thanks for deliberating your flattery ^_^

[mrjohaneson]

@kuhataparunks I'm flattered to hear that I did better than Khan Academy. Thanks.  Only please remember that you must use DEGREES MODE!!!! if you are working with angles in degrees. It's very rare in high school math that you'd be working with radians...until grade 12 math.

[BigA7XDog]

this helps out alot thanx bro