(Take a look at the picture. From the definition of trigonometric ratios in right triangles we have : [tex]\displaystyle { \sin(\angle L)= \frac{opposite \ side}{hypotenuse} = \frac{19}{20}. [/tex] and [tex]\displaystyle { \cos(\angle M)= \frac{adjacent \ side}{hypotenuse} = \frac{19}{20}. [/tex])