Trigonometry is just a

RATIO of 2 sides of a right triangle. So we can set it up as

TRIG(angle) = fraction​

Remember your SOH-CAH-TOA??

S O/H C A/H T O/A

SINE COSINE TANGENT

SINE = OPPOSITE/HYPOTENUESE

​

COSINE = ADJACENT/HYPOTENUESE

​

TANGENT = OPPOSITE/ADJACENT​

​Evaluate Sin/Cos/Tan

Be sure your calculator is in the correct MODE. If you see a degree symbol, make sure you are in DEGREE mode. If you do not see a degree symbol OR if you see π, then choose RADIAN mode.

Calculator -- hit MODE scroll down and select DEGREE or RADIAN

Desmos -- click on the WRENCH top right corner and select DEGREE or RADIAN.

**Default mode for calculators is RADIAN mode.

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Ready to solve for a missing side?​

Start by labeling your sides OPP, ADJ & HYP according to the reference angle (usually labeled or has a measure). Which side has a measure​? Which side are you solving? This will let you know if you are using SIN, COS, or TAN.

TRIG (angle) = side / side Fill in what you know and solve!​

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​Ready to solve for a missing angle?

Like before, label all your sides according to your reference angle (the one you are solving for). Determine if you will use SIN, COS, or TAN. This time you are using an inverse function (the angle and the ratio trade places).

If using a calculator, 2nd SIN/COS/TAN. If using Desmos, click on FUNCTIONS​, Inverse Trig​.

TRIG^-1 (SIDE/SIDE) = missing angle​

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You got this!!