Construct triangle PQR in which PQ = 8cm, angle QPR = 50° and angle PQR = 70°. Measure and write the length of PR.

Draw a ray from $P$ through this mark. This ray will form the side $PR$.

Draw a ray from $Q$ through this mark. This ray will form the side $QR$.

You have now constructed $\triangle PQR$.

The sum of angles in a triangle is $180^\circ$.

The Sine Rule states that for a triangle with sides $a, b, c$ and opposite angles $A, B, C$:

In $\triangle PQR$, we want to find $PR$. We know $PQ = 8$ cm, $\angle PQR = 70^\circ$, and $\angle PRQ = 60^\circ$.
Using the Sine Rule:

Using approximate values for sine: $\sin(70^\circ) \approx 0.9397$ and $\sin(60^\circ) \approx 0.8660$.

Rounding to one decimal place, as is common for measurements:

The length of $PR$ is approximately $\boxed{8.7\, \text{cm}}$.