For right triangles we can use trigonmoetrical ratios if we want calculate the oppisite side of an angle
on this case we use sine to calculate m
where alpha is the angle, O the opposite side of the angle and H the hypotenuse of the triangle
on this triangle
alpha is 45°
the front side is m
and the hypoteuse 7
so replacing
on this point we can solve m form the equation and calulate