To determine the length of the support beam, we can use trigonometric functions.
Let's consider the right triangle formed by the support beam, the vertical post, and the base of the birdhouse. The angle between the support beam and the vertical post is 38°.
In a right triangle, the trigonometric function we can use is the cosine function:

In this case, the adjacent side is the length of the base of the birdhouse, and the hypotenuse is the length of the support beam.

To find the length of the support beam, we can rearrange the equation:

Using a calculator, we can evaluate the cosine of 38°:

Substituting this value into the equation:


Rounding the length of the support beam to the nearest inch, we get:
Approximate length of the support beam,
inches.

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