Using pi = 22/7, find the area of the shaded region.

The diameter is 42 cm, so the radius $r$ is half of the diameter.

The sum of angles around a point is $360^\circ$.
Minor $\angle ROT = 360^\circ - \text{Reflex } \angle ROT$
Minor $\angle ROT = 360^\circ - 240^\circ = 120^\circ$.

Since PR and PT are tangents to the circle at R and T, the radii OR and OT are perpendicular to the tangents at the points of tangency.
Therefore, $\angle ORP = 90^\circ$ and $\angle OTP = 90^\circ$.
The sum of angles in a quadrilateral is $360^\circ$.
In quadrilateral ORPT:
$\angle RPT + \angle ORP + \angle OTP + \text{Minor } \angle ROT = 360^\circ$
$\angle RPT + 90^\circ + 90^\circ + 120^\circ = 360^\circ$
$\angle RPT + 300^\circ = 360^\circ$
$\angle RPT = 360^\circ - 300^\circ = 60^\circ$.

Consider the right-angled triangle $\triangle ORP$.
We know $\angle ORP = 90^\circ$, $OR = r = 21 \text{ cm}$, and $\angle ROP = \frac{\text{Minor } \angle ROT}{2} = \frac{120^\circ}{2} = 60^\circ$.
Using trigonometry:
$\tan(\angle ROP) = \frac{PR}{OR}$
$\tan(60^\circ) = \frac{PR}{21}$
$PR = 21 \times \tan(60^\circ) = 21 \times \sqrt{3} \text{ cm}$.
$PR \approx 21 \times 1.732 = 36.372 \text{ cm}$.
Since tangents from an external point to a circle are equal, $PT = PR = 21\sqrt{3} \text{ cm}$.

The quadrilateral ORPT can be divided into two congruent right-angled triangles, $\triangle ORP$ and $\triangle OTP$.
Area of $\triangle ORP = \frac{1}{2} \times \text{base} \times \text{height} = \frac{1}{2} \times OR \times PR$
Area of $\triangle ORP = \frac{1}{2} \times 21 \text{ cm} \times 21\sqrt{3} \text{ cm} = \frac{441\sqrt{3}}{2} \text{ cm}^2$.
Area of quadrilateral ORPT = $2 \times \text{Area of } \triangle ORP = 2 \times \frac{441\sqrt{3}}{2} \text{ cm}^2 = 441\sqrt{3} \text{ cm}^2$.
$441\sqrt{3} \approx 441 \times 1.732 = 763.812 \text{ cm}^2$.

Area of sector = $\frac{\theta}{360^\circ} \times \pi r^2$
Area of minor sector ROT = $\frac{120^\circ}{360^\circ} \times \frac{22}{7} \times (21 \text{ cm})^2$
Area of minor sector ROT = $\frac{1}{3} \times \frac{22}{7} \times 441 \text{ cm}^2$
Area of minor sector ROT = $\frac{1}{3} \times 22 \times 63 \text{ cm}^2$
Area of minor sector ROT = $22 \times 21 \text{ cm}^2 = 462 \text{ cm}^2$.

The shaded region is the area of the quadrilateral ORPT minus the area of the minor sector ROT.
Area of shaded region = Area of quadrilateral ORPT - Area of minor sector ROT
Area of shaded region = $441\sqrt{3} \text{ cm}^2 - 462 \text{ cm}^2$
Area of shaded region $\approx 763.812 \text{ cm}^2 - 462 \text{ cm}^2 = 301.812 \text{ cm}^2$.

Rounding to two decimal places:
Area of shaded region $\approx \boxed{301.81 \text{ cm}^2}$.