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Ch. 1 - Trigonometric Functions
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161Not the one you use?Change textbook
Chapter 2, Problem 31

Find the measure of each marked angle. See Example 2 complementary angles with measures 9𝓍 + 6 and 3𝓍 degrees

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1
Recall that complementary angles are two angles whose measures add up to 90 degrees. So, set up the equation: \( (9x + 6) + 3x = 90 \).
Combine like terms on the left side of the equation: \( 9x + 6 + 3x = 90 \) becomes \( 12x + 6 = 90 \).
Isolate the variable term by subtracting 6 from both sides: \( 12x = 90 - 6 \) which simplifies to \( 12x = 84 \).
Solve for \(x\) by dividing both sides by 12: \( x = \frac{84}{12} \).
Once you find \(x\), substitute it back into the expressions for the angles \$9x + 6\( and \)3x$ to find the measure of each marked angle.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Complementary Angles

Complementary angles are two angles whose measures add up to 90 degrees. Understanding this relationship allows you to set up an equation where the sum of the given angle expressions equals 90, which is essential for solving for the variable.
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