The half angle formula is: sin x/2 = +/- √ (( 1-cos x ) / 2 ) 5π/12 = 5π/6 : 2 sin 5π/12 = +/- √(( 1 - cos ( 5π/6)) / 2 ) cos 5π/6 = cos 150° = -√3/2 ≈ 0.966 ( this is sin 5π/12 )
Since we know a square has 4 equal sides and is equal to to exact right triangles. USing the formula for Perimeter l+l+w+w=P or 2L+2W=P 56cm÷4=14 so now we have (2)14+(2)14=P P=14cm^2 The slant length on a triangle is equal to L Slant lenght=14