The answer is choice C
Plane D(choice C) because choice a and b are not lines(one letter cannot be a line and PBC and not connected). It's not d because e isn't a point
Answer:
cos(a + b) = 
Step-by-step explanation:
cos(a + b) = cos(a).cos(b) - sin(a).sin(b) [Identity]
cos(a) = 
cos(b) = 
Since, terminal side of angle 'a' lies in quadrant 3, sine of angle 'a' will be negative.
sin(a) =
[Since, sin(a) =
]
= 
= 
Similarly, terminal side of angle 'b' lies in quadrant 2, sine of angle 'b' will be negative.
sin(b) =
= 
= 
By substituting these values in the identity,
cos(a + b) = 
= 
= 
= 
Therefore, cos(a + b) = 
Answer:
1/92^7
this is correct answer of this question
hope it helps
Multiply the numerator and denominator by √2
10√2/2
Simplify
5√2