Find one value of θ or x that satisfies each of the following.
cot(θ - 10°) = tan(2θ - 20°)

검증된 단계별 안내

Recall the identity that relates cotangent and tangent: \(\cot A = \tan(90^\circ - A)\). Use this to rewrite \(\cot(\theta - 10^\circ)\) as \(\tan\big(90^\circ - (\theta - 10^\circ)\big)\).

Rewrite the equation \(\cot(\theta - 10^\circ) = \tan(2\theta - 20^\circ)\) as \(\tan\big(90^\circ - (\theta - 10^\circ)\big) = \tan(2\theta - 20^\circ)\).

Simplify the expression inside the tangent on the left side: \(90^\circ - (\theta - 10^\circ) = 90^\circ - \theta + 10^\circ = 100^\circ - \theta\).

Set the arguments of the tangent functions equal to each other, considering the periodicity of tangent: \(100^\circ - \theta = 2\theta - 20^\circ + k \times 180^\circ\), where \(k\) is any integer.

Solve the resulting linear equation for \(\theta\) to find one or more values that satisfy the original equation.

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주요 개념

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Relationship Between Cotangent and Tangent

Cotangent and tangent are reciprocal trigonometric functions, where cot(α) = 1/tan(α). Recognizing that cot(θ - 10°) can be rewritten as tan(90° - (θ - 10°)) helps transform the equation into a more solvable form by using complementary angle identities.

Trigonometric Equation Solving Techniques

Solving equations involving trigonometric functions often requires using identities, algebraic manipulation, and understanding periodicity. Equating angles or their related expressions and considering the periodic nature of tangent and cotangent functions is essential to find valid solutions.

Angle Identities and Complementary Angles

The identity tan(90° - x) = cot(x) links tangent and cotangent through complementary angles. Applying this identity allows rewriting cot(θ - 10°) as tan(100° - θ), enabling the equation to be expressed in terms of tangent functions for easier comparison and solution.

Find one value of θ or x that satisfies each of the following.cot(θ - 10°) = tan(2θ - 20°)