Hint:
Pythagorus's theorem:
“In any triangle right-angled at B, the lenght of the hypotenuse squared is equal to the sum of the squares of the lenghts of the two other sides” or, in other words:
AC²=AB²+BC²
Trigonometric functions:
In a right triangle, for any non-right angle α:
\(\sin(\alpha)=\frac{\text{opposite side}}{\text{hypotenuse}} \\\cos(\alpha)=\frac{\text{adjacent side}}{\text{hypotenuse}} \\\tan(\alpha)=\frac{\text{opposite side}}{\text{adjacent side}}\)
Respectively the sinus, the cosinus and the tangent of α.
