1. Two of the main identities used in trigonometry for right triangles (Triangles that have an angle of 90°) are: Sine (Sin) and Cosine (Cos).
Sin x°=Opposite/Hypotenuse
Cos x°=Adjacent/Hypotenuse
2. The inverse of Sinx° is Cosec x°, then:
Cosec x°=1/Sin x°
3. The inverse of Cos x° is Sec x°, then:
Sec x°=1/Cos x°
4. Keeping this on mind, you have:
Cosc x°=Hypotenuse/Opposite
Sec x°=Hypotenuse/Adjacent
5. Therefore, the correct answer is:
The third option: Cosec x°=Hypotenuse/Opposite.