so, this triangle is an "impossible' triangle, b/c even when the 5 and 4 sides are laid out, in opposite directions, they only make a distance of 9. so the side of 12 is not ever going to work in this triangle, it's just too long. so the answer is none of the choices are correct. To be fair, this question is incorrect. The picture that is drawn, makes it look like the triangle could be real. when it's not. like an Escher drawing. if you don't know Escher drawings look them up
AC=x, BC=x√3, AB is a hypotenuse (look at the pic below) x√3>x, consequently ∠B<∠A and we have to find cosB, which is (x√3)/AB. <em>Let's find AB:</em> AB=√(x²+(x√3)²)=√(x²+3x²)=√(4x²)=2x <em>Thus, cosB is:</em> cosB=(x√3)/(2x)=√3/2
