Find cos O if sinO = sqrt2/2 is in the second quadrant

D.

Step-by-step explanation:

So, on a regular coordinate plane, coordinates are written (x,y)

well, in trig, coordinates are written (cosθ, sinθ).

if sinθ= in the second quadrant, then look for the "y-value" that says

if you don't have a unit circle to look at, then it helps to know that the fraction is ONLY found with ITSELF OR THE NEGATIVE OF ITSELF. it is never paired with another number.

this means that this number will only be seen in the coordinates

use this knowledge along with knowing the signs in each quadrant:

Q1: (+,+)

Q2: (–,+)

Q3: (–,–)

Q4: (+,–)

attachment?

step-by-step explanation: