Concept

Cosecant

For an acute angle θ of a right triangle, the cosecant of θ is the ratio between the lengths of the hypotenuse and the opposite side.

Sides of a right triangle labeled

The cosecant of θ is written as csc(θ).

csc(θ)=hypotenuse/opposite

This trigonometric ratio states the ratio between the hypotenuse and the opposite side to a certain angle. It gives no indication about the lengths of the sides.

Right triangle with two vertices movable and the cosecant of one acute angle is computed while the measures change

When the opposite side and hypotenuse lengths change for a given angle, if their ratio stays the same then the cosecant, too, would stay the same. Also note that the cosecant of θ is the reciprocal of the sine of θ. csc θ=hyp/opp sin θ =opp/hyp ⇒ csc θ = 1/sin θ

Exercises
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