It should be 0.88 or 0.84
This is an example of the
difference of squares.

So to find the product of <span>(9y</span>²<span> – 4x)(9y</span>²<span> + 4x), we use the formula for the difference of squares.
</span>

<span>
</span>
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) = 
Not enough info
i need more info
que?