Two sides of a right angle triangle are 17cm and 8cm. Find the 3rd side.

We have a right-angled triangle with an angle of $30^\circ$.
The hypotenuse (the side opposite the right angle) is $8 \text{ cm}$.
We need to find the length of the side opposite the $30^\circ$ angle, which is labeled $x$.
We are given $\sin(30^\circ) = 0.5$.

The sine of an angle in a right-angled triangle is defined as the ratio of the length of the opposite side to the length of the hypotenuse:

Substitute the given values into the formula:

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

To find $x$, multiply both sides of the equation by $8 \text{ cm}$:

The calculated value for $x$ is $4 \text{ cm}$.
The options are:
(A) $5.00 \text{ m}$
(B) $4.50 \text{ m}$
(C) $4.62 \text{ m}$
(D) $4.00 \text{ m}$

Although the unit in option (D) is meters, the numerical value 4.00 matches our calculated value of 4. Given the context of the diagram showing sides in centimeters, it is highly probable that the unit in option (D) is a typo and should be centimeters.

The correct option is (D).
The value of $x$ is $\boxed{\text{4.00 cm}}$.