Given S = 90˚ , T = 30˚
R = 180-(90+30) = 60˚ [Sum of angles of triangle is equal to 180˚]
RST is a 30˚ – 60˚- 90˚ triangle
RS = ½ RT [Side opposite to 30˚]
RS = ½ ×12 = 6
ST = √3/2 RT [side opposite to 60˚]
ST = (√3/2 )×12
ST = 6√3
Hence RS = 6 cm and ST = 6√3cm.