Try another version of this question Get help: Box 1: Enter your answer as a number (like 5, -3, 2.2172) or as a calculation (like 5/3, 2^3, 5+4)
If `sin(theta) = -(2sqrt(10))/7` and `theta` is in the 3rd quadrant, find the exact value of `cos(theta)`
`cos(theta)` =
Enter DNE for Does Not Exist, oo for Infinity
Decimal values are not allowed
Trig functions (sin,cos,etc.) are not allowed `-3/7`