*see attached image* Hi, my tutor sent this to me and I'm confused about what -1 represents. If anyone can give me a detailed solution to this question it would be greatly appreciated

Sin, Cos, Tan and others are used to calculate the ratios of the sides of a right angled triangle by taking a certain angle as the angle of reference.

On the other hand, Sin‐¹, Cos‐¹ and Tan-¹ are used to find the reference angle used to calculate the ratio of sides.

For this question,

we need to find which option should used to calculate the angle the slide makes with the vertical support.

So the option will have to be either A, C or E.

here, the base is 2.81m and hypotenuse is 3.64m.

we know, Cos = base / hypotenuse

So the angle is given by Cos-¹(2.81/3.64)

Option C

step-by-step explanation: