Consider right triangle ABC.
A triangle ABC has right angle at B is shown. Base AB has length labeled 40 units. Height BC has length labeled 9 units, and hypotenuse AC has length 41 units.
sin(A) =
=
cos(A) =
=
To find sin(A), we use the formula sin(A) = opposite/hypotenuse. In this case, the opposite side is BC with length 9 units, and the hypotenuse is AC with length 41 units. Therefore,
sin(A) = 9/41
To find cos(A), we use the formula cos(A) = adjacent/hypotenuse. Since A is the acute angle in this case, the adjacent side is AB with length 40 units, and the hypotenuse is AC with length 41 units. Therefore,
cos(A) = 40/41