Evaluate cosθ if sinθ = sqrt5/3

2/3

Step-by-step explanation:

sinθ is opposite/hypotenuse (soh cah toa)

If given what sinθ is, you have the opposite leg to θ and the hypotenuse. It helps to draw a triangle. You can figure out the adjacent leg using the pythagorean theorem. - = 4

Square root 4 to find the adjacent leg, 2.

To find cosθ, which is adjacent over hypotenuse, substitute in the respective numbers, which gives you 2/3.

The correct option is 1:  If neither the volunteers nor the psychiatrist knew which treatment any person had received

Step-by-step explanation:

Consider the provided information.

Fifty are selected at random and are given a new drug and the other 50 are given an existing drug for treating severe depression. A psychiatrist evaluates the symptoms of all volunteers after 4 weeks in order to determine if there has been substantial improvement in the severity of the depression.

An experiment is said to be a double-blind study if the crucial aspects of the experiment are not revealed to either participants or experimenters

Now use the above definition to identify the correct option.

Option 1. If neither the volunteers nor the psychiatrist knew which treatment any person had received.

This option is correct because neither the participants or experimenters know the crucial aspects of the experiment.

Option 2, 3 and 4 are not correct as they don't interpret the correct meaning of double blind study.

Hence, option 1 is correct.