Skip to main content
Ch. 2 - Acute Angles and Right Triangles
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161, 9780135440780, 9780136881117, 9780135440827, 9780135924891Non è quello che usi tu?Cambia libro di testo
Capitolo 3, Problema 18

Suppose ABC is a right triangle with sides of lengths a, b, and c and right angle at C. Use the Pythagorean theorem to find the unknown side length. Then find exact values of the six trigonometric functions for angle B. Rationalize denominators when applicable. See Example 1. a = √2, c = 2

Guida verificata passo dopo passo
1
Identify the sides of the right triangle ABC, where the right angle is at C. This means side c is the hypotenuse, and sides a and b are the legs opposite angles A and B respectively.
Use the Pythagorean theorem, which states \(a^2 + b^2 = c^2\), to find the unknown side length \(b\). Substitute the known values \(a = \sqrt{2}\) and \(c = 2\) into the equation: \(\left(\sqrt{2}\right)^2 + b^2 = 2^2\).
Simplify the equation to solve for \(b^2\): \(2 + b^2 = 4\), then isolate \(b^2\) by subtracting 2 from both sides to get \(b^2 = 2\). Finally, take the positive square root to find \(b = \sqrt{2}\), since side lengths are positive.
Now, find the six trigonometric functions for angle B. Recall the definitions relative to angle B: \(\sin B = \frac{\text{opposite}}{\text{hypotenuse}} = \frac{a}{c}\), \(\cos B = \frac{\text{adjacent}}{\text{hypotenuse}} = \frac{b}{c}\), and \(\tan B = \frac{\text{opposite}}{\text{adjacent}} = \frac{a}{b}\). Use the values \(a = \sqrt{2}\), \(b = \sqrt{2}\), and \(c = 2\) to write these ratios.
Next, find the reciprocal functions: \(\csc B = \frac{1}{\sin B}\), \(\sec B = \frac{1}{\cos B}\), and \(\cot B = \frac{1}{\tan B}\). Simplify each expression and rationalize denominators where necessary to express the exact values.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
8m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Pythagorean Theorem

The Pythagorean theorem states that in a right triangle, the square of the hypotenuse (side opposite the right angle) equals the sum of the squares of the other two sides. It is expressed as a² + b² = c². This theorem allows you to find an unknown side length when the other two are known.
Video consigliato:
Percorso guidato
5:19
Solving Right Triangles with the Pythagorean Theorem

Trigonometric Functions in Right Triangles

The six trigonometric functions—sine, cosine, tangent, cosecant, secant, and cotangent—relate the angles of a right triangle to the ratios of its sides. For an angle, sine is opposite/hypotenuse, cosine is adjacent/hypotenuse, and tangent is opposite/adjacent. The reciprocal functions are cosecant, secant, and cotangent.
Video consigliato:
Percorso guidato
6:04
Introduction to Trigonometric Functions

Rationalizing Denominators

Rationalizing the denominator involves eliminating any square roots or irrational numbers from the denominator of a fraction. This is done by multiplying numerator and denominator by a suitable expression, often the conjugate or the root itself, to simplify the expression and present it in a standard form.
Video consigliato:
Percorso guidato
2:58
Rationalizing Denominators