Use a calculator to determine whether each statement is true or false. A true statement may lead to results that differ in the last decimal place due to rounding error. cos 40° = 2 cos 20°
Table of contents
- 0. Review of College Algebra4h 45m
- 1. Measuring Angles40m
- 2. Trigonometric Functions on Right Triangles2h 5m
- 3. Unit Circle1h 19m
- 4. Graphing Trigonometric Functions1h 19m
- 5. Inverse Trigonometric Functions and Basic Trigonometric Equations1h 41m
- 6. Trigonometric Identities and More Equations2h 34m
- 7. Non-Right Triangles1h 38m
- 8. Vectors2h 25m
- 9. Polar Equations2h 5m
- 10. Parametric Equations1h 6m
- 11. Graphing Complex Numbers1h 7m
6. Trigonometric Identities and More Equations
Introduction to Trigonometric Identities
Multiple Choice
Select the expression with the same value as the given expression.
sin(−38°)
A
sin38°
B
−sin38°
C
−sin(−38°)
D
−sin38°1
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Verified step by step guidance1
Understand the property of the sine function: \( \sin(-x) = -\sin(x) \). This property states that the sine of a negative angle is the negative of the sine of the positive angle.
Apply the property to the given expression \( \sin(-38\degree) \). Using the property, we can rewrite this as \( -\sin(38\degree) \).
Compare the rewritten expression \( -\sin(38\degree) \) with the options provided.
Identify that \( -\sin(38\degree) \) matches one of the options given, which is \( -\sin(38\degree) \).
Conclude that the expression \( \sin(-38\degree) \) is equivalent to \( -\sin(38\degree) \) based on the trigonometric identity.
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