Evaluate each expression without using a calculator. tan (arcsin (3/5) + arccos (5/7))
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Identify the problem as evaluating \( \tan(\arcsin(\frac{3}{5}) + \arccos(\frac{5}{7})) \).
Recognize that \( \arcsin(\frac{3}{5}) \) represents an angle whose sine is \( \frac{3}{5} \). Use the Pythagorean identity to find the cosine of this angle: \( \cos(\theta) = \sqrt{1 - \sin^2(\theta)} = \sqrt{1 - (\frac{3}{5})^2} \).
Similarly, \( \arccos(\frac{5}{7}) \) represents an angle whose cosine is \( \frac{5}{7} \). Use the Pythagorean identity to find the sine of this angle: \( \sin(\phi) = \sqrt{1 - \cos^2(\phi)} = \sqrt{1 - (\frac{5}{7})^2} \).
Use the angle addition formula for tangent: \( \tan(\theta + \phi) = \frac{\tan(\theta) + \tan(\phi)}{1 - \tan(\theta)\tan(\phi)} \).
Calculate \( \tan(\theta) = \frac{\sin(\theta)}{\cos(\theta)} \) and \( \tan(\phi) = \frac{\sin(\phi)}{\cos(\phi)} \), then substitute these into the angle addition formula to find \( \tan(\theta + \phi) \).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Inverse Trigonometric Functions
Inverse trigonometric functions, such as arcsin and arccos, are used to find angles when given a ratio of sides in a right triangle. For example, arcsin(3/5) gives the angle whose sine is 3/5, while arccos(5/7) gives the angle whose cosine is 5/7. Understanding these functions is crucial for evaluating expressions involving angles derived from trigonometric ratios.
The sum of angles formula for tangent states that tan(A + B) = (tan A + tan B) / (1 - tan A * tan B). This formula allows us to evaluate the tangent of the sum of two angles, which is essential for solving the given expression. Knowing how to apply this formula is key to simplifying the expression involving arcsin and arccos.
Verifying Identities with Sum and Difference Formulas
Pythagorean Identity
The Pythagorean identity states that for any angle θ, sin²(θ) + cos²(θ) = 1. This identity is useful for finding the sine and cosine values of angles derived from inverse trigonometric functions. In the context of the problem, it helps to determine the tangent values needed to apply the sum of angles formula effectively.