Math Problem Statement

KLM is a triangle with m(∠K)=30∘. If KL=10 units, and tan(M)=1/2, then find the length of KM. Hint: Draw a picture and include the altitude from the angle L to the side KM.

Solution

Let's solve this step by step.

Step 1: Analyze the given information

  • We are given a triangle KLMKLM, with the measure of K=30\angle K = 30^\circ.
  • KL=10KL = 10 units.
  • tan(M)=12\tan(\angle M) = \frac{1}{2}.

We need to find the length of KMKM.

Step 2: Draw a diagram

Draw a triangle KLMKLM. Place KK at the origin of a coordinate system, with LL and MM at two other points. Now, draw the altitude from point LL perpendicular to KMKM, meeting KMKM at point PP. This divides KLM\triangle KLM into two right triangles, KLP\triangle KLP and LPM\triangle LPM.

Step 3: Use trigonometric relations

In KLP\triangle KLP:

  • Since K=30\angle K = 30^\circ, and we know KL=10KL = 10, we can find the length of the altitude LPLP and the projection KPKP using basic trigonometry.

  • For the altitude LPLP, we use: sin(30)=LPKL\sin(30^\circ) = \frac{LP}{KL} sin(30)=LP10\sin(30^\circ) = \frac{LP}{10} Since sin(30)=12\sin(30^\circ) = \frac{1}{2}: 12=LP10LP=5 units.\frac{1}{2} = \frac{LP}{10} \quad \Rightarrow \quad LP = 5 \text{ units}.

  • For the base KPKP, we use: cos(30)=KPKL\cos(30^\circ) = \frac{KP}{KL} cos(30)=KP10\cos(30^\circ) = \frac{KP}{10} Since cos(30)=32\cos(30^\circ) = \frac{\sqrt{3}}{2}: 32=KP10KP=53 units.\frac{\sqrt{3}}{2} = \frac{KP}{10} \quad \Rightarrow \quad KP = 5\sqrt{3} \text{ units}.

In LPM\triangle LPM:

  • From the given tan(M)=12\tan(\angle M) = \frac{1}{2}, we know: tan(M)=LPPM=5PM.\tan(\angle M) = \frac{LP}{PM} = \frac{5}{PM}. Therefore, PM=10PM = 10 units.

Step 4: Find the length of KMKM

Now, we can find KMKM by adding the lengths of KPKP and PMPM: KM=KP+PM=53+10.KM = KP + PM = 5\sqrt{3} + 10. Thus, the length of KMKM is 53+105\sqrt{3} + 10 units.

Summary

The length of KMKM is 53+105\sqrt{3} + 10 units.


Would you like further clarification on any step, or do you have any questions?

Here are five follow-up questions to consider:

  1. What is the geometric significance of the altitude in a triangle?
  2. How can you use the tangent function to find other unknown sides in a right triangle?
  3. How would the problem change if tan(M)\tan(M) had a different value?
  4. What would be the impact if K\angle K were greater than 3030^\circ?
  5. Can the Pythagorean theorem be used here? If so, how?

Tip: In any triangle, altitudes are useful tools for creating right triangles and applying trigonometric functions effectively.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Right Triangle
Tangent Function
Sine and Cosine Functions

Formulas

sin(θ) = Opposite/Hypotenuse
cos(θ) = Adjacent/Hypotenuse
tan(θ) = Opposite/Adjacent

Theorems

Trigonometric Identities
Pythagorean Theorem

Suitable Grade Level

Grades 9-11