Solve each right triangle. When two sides are given, give angles in degrees and minutes. See Examples 1 and 2.
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
2. Trigonometric Functions on Right Triangles
Solving Right Triangles
Problem 30
Textbook Question
Solve each right triangle. In each case, C = 90°. If angle information is given in degrees and minutes, give answers in the same way. If angle information is given in decimal degrees, do likewise in answers. When two sides are given, give angles in degrees and minutes. See Examples 1 and 2. B = 51.7°, a = 28.1 ft
Verified step by step guidance1
Identify the given elements of the right triangle: angle \( B = 51.7^\circ \), side \( a = 28.1 \) ft, and the right angle \( C = 90^\circ \). Recall that side \( a \) is opposite angle \( A \), side \( b \) is opposite angle \( B \), and side \( c \) is the hypotenuse opposite the right angle \( C \).
Calculate angle \( A \) using the fact that the sum of angles in a triangle is \( 180^\circ \). Since \( C = 90^\circ \), use the formula: \( A = 90^\circ - B \).
Use the Law of Sines to find the hypotenuse \( c \). The Law of Sines states: \( \frac{a}{\sin A} = \frac{c}{\sin C} \). Since \( C = 90^\circ \), \( \sin C = 1 \), so \( c = \frac{a}{\sin A} \).
Find side \( b \) using the Law of Sines again or by using the Pythagorean theorem. Using Law of Sines: \( b = c \times \sin B \). Alternatively, use \( b = \sqrt{c^2 - a^2} \).
Express all answers with the correct units and in decimal degrees as given. Since the angle \( B \) was given in decimal degrees, keep angles \( A \) and \( B \) in decimal degrees, and sides in feet.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Right Triangle Properties
A right triangle has one angle equal to 90°, and the other two angles sum to 90°. Knowing one acute angle and a side allows the use of trigonometric ratios to find unknown sides and angles. The right angle simplifies calculations and ensures the Pythagorean theorem applies.
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30-60-90 Triangles
Trigonometric Ratios (Sine, Cosine, Tangent)
Sine, cosine, and tangent relate the angles of a right triangle to the ratios of its sides. For example, sine of an angle equals the opposite side over the hypotenuse. These ratios help find missing sides or angles when some measurements are known.
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Sine, Cosine, & Tangent of 30°, 45°, & 60°
Angle Measurement and Conversion
Angles can be expressed in degrees and minutes or decimal degrees. Understanding how to convert between these formats is essential for accurate answers. For instance, 0.7° equals 42 minutes (0.7 × 60), ensuring consistency with the problem's requirements.
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Reference Angles on the Unit Circle
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