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If A, B, C are angles of Delta ABC and ...

If `A, B, C` are angles of `Delta ABC` and `tan A tan C = 3, tan B tan C = 6`, then

A

`A=(pi)/(4)`

B

`tanA tanB=2`

C

`(tanA)/(tanC)=3`

D

`tanB=2tanA`

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The correct Answer is:
To solve the problem, we are given the following equations based on the angles of triangle ABC: 1. \( \tan A \tan C = 3 \) (Equation 1) 2. \( \tan B \tan C = 6 \) (Equation 2) Since \( A + B + C = 180^\circ \), we can express \( B \) in terms of \( A \) and \( C \): \[ B = 180^\circ - A - C \] Using the tangent subtraction formula: \[ \tan(180^\circ - x) = -\tan x \] Thus, \[ \tan B = -\tan(A + C) = -\frac{\tan A + \tan C}{1 - \tan A \tan C} \] Now substituting \( \tan A \tan C = 3 \) into the equation for \( \tan B \): \[ \tan B = -\frac{\tan A + \tan C}{1 - 3} \] \[ \tan B = -\frac{\tan A + \tan C}{-2} = \frac{\tan A + \tan C}{2} \] Now we can substitute \( \tan B \) into Equation 2: \[ \frac{\tan A + \tan C}{2} \tan C = 6 \] Multiplying both sides by 2: \[ (\tan A + \tan C) \tan C = 12 \] Now we can express \( \tan A \) in terms of \( \tan C \): From Equation 1, we have: \[ \tan A = \frac{3}{\tan C} \] Substituting this into the equation: \[ \left(\frac{3}{\tan C} + \tan C\right) \tan C = 12 \] \[ 3 + \tan^2 C = 12 \] \[ \tan^2 C = 12 - 3 = 9 \] \[ \tan C = 3 \quad \text{(since tangent is positive in a triangle)} \] Now substituting \( \tan C = 3 \) back into Equation 1 to find \( \tan A \): \[ \tan A \cdot 3 = 3 \implies \tan A = 1 \] Thus, \[ A = 45^\circ \] Now substituting \( \tan C = 3 \) into Equation 2 to find \( \tan B \): \[ \tan B \cdot 3 = 6 \implies \tan B = 2 \] Thus, \[ B = \tan^{-1}(2) \] Finally, we can find \( C \): \[ C = 180^\circ - A - B = 180^\circ - 45^\circ - \tan^{-1}(2) \] ### Summary of Results: - \( A = 45^\circ \) - \( B = \tan^{-1}(2) \) - \( C = 180^\circ - 45^\circ - \tan^{-1}(2) \)
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