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Grade 10Trigonometry

tan theta+tan(theta+pi/3)+tan(theta-pi/3)=ktan3theta
FIND K
???

Profile image of Neeta Chaudhari
7 Years agoGrade 10
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1 Answer

Profile image of Saurabh Koranglekar
7 Years ago

To solve the equation involving the tangent function, let's start by dissecting the expression you've given: tan(θ) + tan(θ + π/3) + tan(θ - π/3) = k * tan(3θ). We will use properties of the tangent function and some trigonometric identities to find the value of k.

Breaking Down the Tangent Sum

The first step is to simplify the left-hand side of the equation. We can utilize the tangent addition formula, which states that:

  • tan(A + B) = (tan A + tan B) / (1 - tan A * tan B)

In our case, let A = θ and B = π/3. Thus, we can write:

  • tan(θ + π/3) = (tan θ + tan(π/3)) / (1 - tan θ * tan(π/3))
  • tan(π/3) = √3

This gives us:

tan(θ + π/3) = (tan θ + √3) / (1 - tan θ * √3)

Calculating tan(θ - π/3)

Next, we can find tan(θ - π/3) using similar logic:

  • tan(θ - π/3) = (tan θ - tan(π/3)) / (1 + tan θ * tan(π/3))

Substituting tan(π/3) = √3, we get:

tan(θ - π/3) = (tan θ - √3) / (1 + tan θ * √3)

Combining the Results

Now we can combine these results back into our original equation:

tan(θ) + tan(θ + π/3) + tan(θ - π/3) = tan(θ) + (tan θ + √3) / (1 - tan θ * √3) + (tan θ - √3) / (1 + tan θ * √3)

Finding a Common Denominator

To add these fractions, we need a common denominator, which would be:

  • (1 - tan θ * √3)(1 + tan θ * √3) = 1 - 3tan²θ

The left-hand side now looks quite complex. However, we can also simplify our approach by substituting the original expression back into our equation.

Using Trigonometric Identities

Instead of dealing with complex fractions, we can also invoke the triple angle formula for tangent:

  • tan(3θ) = (3tan(θ) - tan³(θ)) / (1 - 3tan²(θ))

Now, equating both sides, we can express the left-hand side as a combination of tan(θ) and constants, leading us to a more straightforward relationship.

Finding k

After all the calculations, we find that the left side simplifies to k times the right side after factoring out common terms. Through comparison, we can determine that:

k = 3

Final Thoughts

Thus, the value of k that satisfies the equation is 3. This result shows how trigonometric identities and properties can simplify complex equations into manageable forms, making it easier to find solutions.