tolong bantu yah kawan,ini ada tugas

4/sin 60° = pr/sin 90°
4/ 1/2 akar 2 = pr/1
pr = 4/ 1/2 akar 2 × akar 2/ akar 2
pr = 4 akar 2 / 1/2 × 2
pr = 4 akar 2