In this case, we'll have to carry out several steps to find the solution.
Step 01:
Data
angle = 30°
opposite = QR = 7
RS = ?
QS = ?
Step 02:
tan α = opposite / adjacent
RS = adjacent
tan 30 = 7 / RS
RS * tan 30 = 7
RS = 7 / tan 30 = 7 / (√3 / 3) = 7 * 3 / √3 = 21 / √3 = 7 √3
QS = hypotenuse
sin α = opposite / hypotenuse
sin 30 = 7 / QS
QS * sin 30 = 7
QS = 7 / sin 30 = 7 / (1 /2) = 14
The answer is:
RS = 7 √3
QS = 14