If KM and KL are tangent to the circle, angle LFK = 23 degrees and KM = 47 ft, how long is LF to the nearest foot?

1 answer

To find the length of segment \( LF \), we can use some properties of circles and the relationship between tangents and angles.

Given:

  • \( KM \) and \( KL \) are tangents to the circle.
  • \( KM = 47 , \text{ft} \).
  • \( \angle LFK = 23^\circ \).

From the properties of tangents to a circle:

  1. The angle between a tangent and a radius drawn to the point of contact is \( 90^\circ \).
  2. The tangents \( KM \) and \( KL \) are equal in length because they are tangents from the same external point \( K \).

Thus, we have:

  • \( KL = 47 , \text{ft} \).

Now, consider triangle \( KLF \):

  • Since both \( KM \) and \( KL \) are tangents, there is a right triangle formed with the radius at the point of tangency to side \( LF \) (which connects \( L \) and \( F \)), meaning \( \angle KLF = 90^\circ \).

To determine \( LF \), we can apply the tangent function in triangle \( KLF \):

  • We know \( \angle LFK = 23^\circ \) and that the opposite side to \( \angle LFK \) is \( LF \) and the adjacent side is \( KL \).

Using the tangent function: \[ \tan(\angle LFK) = \frac{LF}{KL} \] Substituting the known values: \[ \tan(23^\circ) = \frac{LF}{47} \]

Now, calculate \( \tan(23^\circ) \): \[ \tan(23^\circ) \approx 0.4245 \]

We then substitute this back into our equation: \[ 0.4245 = \frac{LF}{47} \]

Solving for \( LF \): \[ LF = 47 \times 0.4245 \approx 19.94 \]

Rounded to the nearest foot, \( LF \) is: \[ \text{Length of } LF \approx 20 \text{ ft}. \]

Thus, the length of \( LF \) to the nearest foot is \( \boxed{20} \).