Since this is a right triangle, we can use one of the three main trigonometric functions: sine, cosine, or tangent.
Remember: SOH-CAH-TOA
Looking from angle I, we know the opposite side and the hypotenuse. Therefore, we should use sine.
sin(I) = [tex]\frac{\sqrt{39}}{\sqrt{51}}[/tex]
To solve, you can use your calculator and the inverse sine function (sin^-1).
I = sin^-1([tex]\frac{\sqrt{39}}{\sqrt{51}}[/tex])
I = 61 degrees
Hope this helps!
