$$\cos A = \tan(90^\circ - A)$$

Question 1

Which of the following is a correct cofunction identity for complementary angles?

Accepted Answer

$$\sin A = \cos(90^\circ - A)$$

Question 2

If $$\cos(27^\circ) = x$$, which of the following is equivalent to $$x$$ using a cofunction identity?

Accepted Answer

$$\sin(63^\circ)$$

Question 3

Which trigonometric function is the cofunction of $$	an A$$?

Accepted Answer

$$\cot(90^\circ - A)$$

Question 4

Given $$\sec(10^\circ) = \csc(80^\circ)$$, which identity justifies this equality?

Accepted Answer

$$\sec A = \csc(90^\circ - A)$$

Question 5

If $$	an(25^\circ) = x$$, what is $$x in $$terms of a cofunction?

Accepted Answer

$$\cot(65^\circ)$$

Question 6

Solve for $$x in $$degrees: $$\cos(2x + 15) = \sin(34 + x).$$

Accepted Answer

$$4$$

Question 7

Which of the following is NOT a cofunction identity?

Accepted Answer

$$\cos A = 	an(90^\circ - A)$$

Question 8

If $$\cos(\frac{7x}{5} + 20) = \sin(\frac{2x}{5} + 17)$$, what is the value of $$x in $$degrees?

Accepted Answer

$$17$$

Question 9

Express $$\cot(25^\circ) in $$terms of its cofunction.

Accepted Answer

$$	an(65^\circ)$$

Question 10

If $$	an\left(\frac{\pi}{2} - xight) = \cos(x - 1)$$, what is the value of $$x in $$radians?

Accepted Answer

$$1$$

Question 11

A right triangle has angles $$A$$ and $$B$$ such that $$A + B = 90^\circ. $$Which statement is true?

Accepted Answer

$$\sin A = \cos B$$

Question 12

Which cofunction identity can be used to solve $$\sin(37^\circ) = \cos(x)$$ for $$x$$?

Accepted Answer

$$\sin A = \cos(90^\circ - A)$$

Question 13

If $$\sin(53^\circ) = \cos(x)$$, what is the value of $$x$$?

Accepted Answer

$$37^\circ$$

Question 14

Which of the following is the correct cofunction for $$\sec A$$?

Accepted Answer

$$\csc(90^\circ - A)$$

Question 15

If $$\sin(90^\circ - x) = \cos(x)$$, what is the value of $$\sin(30^\circ) in $$terms of a cofunction?

Accepted Answer

$$\cos(60^\circ)$$

Cofunctions of Complementary Angles and Cofunction Identities

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