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Ch. 5 - Trigonometric Identities
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161당신이 사용하는 게 아니라요?교과서 변경
6장, 문제 82

Use the result from Exercise 80 to find the acute angle between each pair of lines. (Note that the tangent of the angle will be positive.) Use a calculator, and round to the nearest tenth of a degree.
5x - 2y + 4 = 0, 3x + 5y = 6

검증된 단계별 안내
1
Rewrite each line in slope-intercept form \(y = mx + b\) to identify their slopes. For the first line \(5x - 2y + 4 = 0\), solve for \(y\) to find its slope \(m_1\).
Similarly, rewrite the second line \(3x + 5y = 6\) in slope-intercept form to find its slope \(m_2\).
Use the formula for the tangent of the angle \(\theta\) between two lines with slopes \(m_1\) and \(m_2\): \(\tan(\theta) = \left| \frac{m_1 - m_2}{1 + m_1 m_2} \right|\) This formula gives the absolute value of the tangent of the angle between the lines.
Calculate the value of \(\tan(\theta)\) using the slopes found in steps 1 and 2. Since the problem states the tangent is positive, take the positive value.
Use a calculator to find the angle \(\theta\) by taking the arctangent (inverse tangent) of the value from step 4: \(\theta = \arctan\left( \tan(\theta) \right)\) Round the result to the nearest tenth of a degree to get the acute angle between the lines.

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
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주요 개념

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Angle Between Two Lines

The angle between two lines in a plane can be found using the slopes of the lines. If m1 and m2 are the slopes, the tangent of the angle θ between them is given by |(m1 - m2) / (1 + m1*m2)|. This formula helps determine the acute angle formed where the lines intersect.
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Finding the Slope from a Line Equation

To find the slope of a line given in standard form Ax + By + C = 0, rearrange it into slope-intercept form y = mx + b. The slope m is then -A/B. This step is essential to apply the angle formula between two lines.
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Using a Calculator to Find Angles from Tangent Values

Once the tangent of the angle is calculated, use the inverse tangent function (arctan or tan⁻¹) on a calculator to find the angle in degrees. Since the problem specifies the tangent is positive, the angle found will be acute and should be rounded to the nearest tenth of a degree.
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