In triangle PQR, PR = 7.6 cm and angle PRQ = 30 degrees. If PS is the altitude to QR, find PS.

We have a triangle PQR.
The length of side $PR = 7.6$ cm.
The angle $\angle PRQ = 30^\circ$ (as labeled in the diagram).
Point S is on the side QR.
We need to calculate PS and $\angle PRQ$.

From the diagram, the angle at R, which is $\angle PRQ$, is clearly labeled.

To calculate PS, we must assume that PS is the altitude from P to QR. This means that $\triangle PRS$ is a right-angled triangle with the right angle at S ($\angle PSR = 90^\circ$).
In the right-angled triangle PRS, we can use the sine function:

We know that $\sin(30^\circ) = 0.5$.