Okay - so where did i mess up? so i figured, that the top triangle's missing angle was 30 degrees. so i did 91/cos30 = 105ish for there it was just a tan(60) to get x

Check out the attached image below. I added a variable y to help find x

tan(angle) = opposite/adjacent

Focusing on the smaller 30-60-90 triangle, we see that

tan(60) = 91/y

y*tan(60) = 91

y = 91/tan(60)

y = 52.53887

now focus on the largest triangle and we see that

tan(30) = 91/(x+y)

0.57735 = 91/(x+52.53887)

0.57735*(x+52.53887) = 91

0.57735*x + 0.57735*52.53887 = 91

0.57735*x + 30.3333165945 = 91

0.57735*x + 30.3333165945 - 30.3333165945 = 91 - 30.3333165945

0.57735*x = 60.6666834055

x = 60.6666834055/0.57735

x = 105.07782697757

x = 105.1

So the final answer is approximately 105.1

x = 105.1

Explanation:

Consider two triangles:

small Δ:

    tan 60° =

⇒ y tan 60° = 91

⇒ y =

large Δ:

    tan 30° =

⇒ (x+y) tan 30° = 91

⇒ x + y =

⇒ y = - x

Solve the System:

small Δ: y =

large Δ: y = - x

⇒ = - x

⇒ - = -x

⇒ 52.5 - 157.6 = -x

⇒ -105.1 = -x

⇒ 105.1 = x

Your error was using cos (adjacent/hypotenuse) instead of tan (opposite/adjacent).

unless if u could do my questions, if not i wouldn't want to