5/10 or simplified to 1/2, so I believe angle a is 60 degrees because cos(60) is 1/2, and cos(a)=adj/hyp. Cos(0)=1 cos(30)=√3/2 cos(45)=√2/2 cos(60)=1/2, and knowing by that since it's a right triangle, and we know angle a is 60 degrees, then 60+90+x=180 so angle x is 30 degrees, so it's a 30 60 90 triangle which is a common triangle you will encounter in trigonometry. And we know the hypotenuse is =1, so sin(a) = sqrt(3)/2 so cos(a)^2+sin(a)^2 equals to 1. And it proves to be a 30 60 90 triangle again with the sides being equal to x√3 and x and the hypotenuse 2x which proves it yet again with x=1/2 or cos(a) making each value of sin(a) and cos(a) while still equaling to 1 with 2x=1 and (√3/2)^2+(1/2)^2=1, i know i went on a long math rant but i just love math :D

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