Cofunction

In scalene triangle ABC shown in the diagram below, m∠C = 90°. Which equation is always true?

• 1) sinA = sinB

• 2) cosA = cosB

• 3) cosA = sinC

• 4) sinA = cosB

In triangle ABC below, angle C is a right angle. Which statement must be true?

• 1) sinA = cosB

• 2) sinA = tanB

• 3) sinB = tanA

• 4) sinB = cosB

Which expression is always equivalent to sinx when 0° < x < 90°?

• 1) cos(90° − x)

• 2) cos(45° − x)

• 3) cos(2x)

• 4) cos x

In ABC, the complement of ∠B is ∠A. Which statement is always true?

• 1) tan∠A = tan∠B

• 2) sin∠A = sin∠B

• 3) cos∠A = tan∠B

• 4) sin∠A = cos∠B

In right triangle ABC, m∠C = 90° and AC ≠ BC. Which trigonometric ratio is equivalent to sinB?

• 1) cosA

• 2) cosB

• 3) tanA

• 4) tanB

The expression sin57° is equal to

• 1) tan33°

• 2) cos 33°

• 3) tan57° 4) cos 57°

• 4) cos 57°

In a right triangle, sin(40 − x)° = cos(3x)°. What is the value of x?

• 1) 10

• 2) 15

• 3) 20

• 4) 25

In a right triangle, the acute angles have the relationship sin(2x + 4) = cos(46). What is the value of x?

• 1) 20

• 2) 21

• 3) 24

• 4) 25

If sin(2x + 7)° = cos(4x − 7)°, what is the value of x?

• 1) 7

• 2) 15

• 3) 21

• 4) 30

For the acute angles in a right triangle, sin(4x)° = cos(3x + 13)°. What is the number of degrees in the measure of the smaller angle?

• 1) 11°

• 2) 13°

• 3) 44°

• 4) 52°