Someone please help me understand trig

sin of an angle is across/hypotenuse

cos of an angle is adjacent/hypotenuse

tan of an angle is across/adjacent 

you normally get 2 values of those 3,

so you can use a calculator to find the missing value

Step 1 The two sides we know are Opposite (300) and Adjacent (400).

Step 2 SOHCAHTOA tells us we must use Tangent.

Step 3 Calculate Opposite/Adjacent = 300/400 = 0.75.

Step 4 Find the angle from your calculator using tan-1