Select all the correct answers.If the measure of angle 𝜃 is 3𝜋4 , which statements are true? The measure of the reference angle is 30∘ . cos(𝜃)=22 tan(𝜃)=1 sin(𝜃)=22 The measure of the reference angle is 60∘ . The measure of the reference angle is 45∘ .
Question
Select all the correct answers.If the measure of angle 𝜃 is 3𝜋4 , which statements are true? The measure of the reference angle is 30∘ . cos(𝜃)=22 tan(𝜃)=1 sin(𝜃)=22 The measure of the reference angle is 60∘ . The measure of the reference angle is 45∘ .
Solution
The measure of angle 𝜃 is given as 3𝜋/4. This is in radians and it corresponds to 135 degrees in the unit circle.
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The measure of the reference angle is 30∘: This statement is false. The reference angle is the acute angle that the terminal side of the given angle makes with the x-axis. For an angle of 135 degrees, the reference angle is 45 degrees, not 30 degrees.
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cos(𝜃)=22: This statement is false. The cosine of 135 degrees or 3𝜋/4 radians is -1/√2 or -√2/2, not 22.
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tan(𝜃)=1: This statement is false. The tangent of 135 degrees or 3𝜋/4 radians is -1, not 1.
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sin(𝜃)=22: This statement is false. The sine of 135 degrees or 3𝜋/4 radians is 1/√2 or √2/2, not 22.
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The measure of the reference angle is 60∘: This statement is false. As mentioned earlier, the reference angle for 135 degrees is 45 degrees, not 60 degrees.
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The measure of the reference angle is 45∘: This statement is true. The reference angle for 135 degrees or 3𝜋/4 radians is indeed 45 degrees.
Similar Questions
The measure of angle θ is 7𝜋4. The measure of its reference angle is °, and tan θ is .
𝐴, 𝐵, 𝐶 and 𝐷 are points on a circle.𝑃𝐴 is a tangent to the circle.Angle 𝑃𝐴𝐷=39∘Angle 𝐵𝐶𝐷=103∘Calculate the size of angle 𝐴𝐷𝐵.(5 marks)
(b)If ∠1 and ∠2 are complementary angles, then one of them must have a measure greater than 45°.=Counterexample:m∠1=, °m∠2°
In △𝐴𝐵𝐶, 𝐴𝐵=6𝑐𝑚, 𝐴𝐶=12𝑐𝑚, 𝑚∠𝐴=60∘ and 𝐴𝐶― is the longest side. Which of the following statements about the measures of the angles in △𝐴𝐵𝐶 must be true? (Note: 𝑚∠𝑋 denotes the measure of angle X.)
If ∠1 and ∠2 are complementary angles, then one of them must have a measure greater than 45°.
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