The three main trig functions are sine (written as sin), cosine (written as cos), and tangent (written as tan).
Sine of an angle = the length of the side opposite (aka across) the angle / the length of the hypotenuse
Cosine of an angle = the length of the side adjacent (aka the side next to which isn't the hypotenuse) to the angle / the length of the hypotenuse
Tangent of an angle = the length of the side opposite of the angle / the length of the side adjacent to the angle.
The acronym to remember this is SOHCAHTOA
SOH | CAH | TOA
SOH means sin(x) = opposite/hypotenuse
CAH means cos(x) = adjacent/hypotenuse
TOA means tan(x)= opposite/adjacent
cosB = length of adjacent side/length of hypotenuse = 7/25
tanB = length of opposite/length of adjacent = 24/7
sinB = length of opposite/length of hypotenuse = 24/25