Question: draw triangle PQR such that $[PQ] = 4.5$ cm, $[PR] = 11.7$ cm, $\angle PQR = 90^\circ$
1. **Problem Statement:** Draw triangle $PQR$ where side $PQ = 4.5$ cm, side $PR = 11.7$ cm, and angle $\angle PQR = 90^\circ$.
2. **Understanding the problem:** We have two sides and one angle given. The angle $\angle PQR = 90^\circ$ means the triangle has a right angle at vertex $Q$.
3. **Steps to draw:**
- Draw segment $PQ$ of length $4.5$ cm.
- At point $Q$, construct a $90^\circ$ angle.
- From $Q$, draw a line perpendicular to $PQ$.
- Locate point $R$ on this perpendicular line such that $PR = 11.7$ cm.
4. **Finding coordinates (optional for accuracy):**
- Place $P$ at origin $(0,0)$.
- Place $Q$ at $(4.5,0)$ since $PQ=4.5$ cm along x-axis.
- Since $\angle PQR=90^\circ$, $R$ lies on vertical line through $Q$ at $(4.5,y)$.
- Use distance formula for $PR=11.7$ cm:
$$
PR = \sqrt{(4.5-0)^2 + (y-0)^2} = 11.7
$$
$$
\Rightarrow \sqrt{4.5^2 + y^2} = 11.7
$$
$$
4.5^2 + y^2 = 11.7^2
$$
$$
20.25 + y^2 = 136.89
$$
$$
y^2 = 136.89 - 20.25 = 116.64
$$
$$
y = \pm \sqrt{116.64} = \pm 10.8
$$
5. **Conclusion:** Point $R$ is at $(4.5, 10.8)$ or $(4.5, -10.8)$.
6. **Draw the triangle with points:**
- $P(0,0)$
- $Q(4.5,0)$
- $R(4.5,10.8)$ (choosing positive y for convenience)
This completes the triangle $PQR$ with the given conditions.