Why does $\frac{49}{64}\cos^2 \theta + \cos^2 \theta$ equal $\frac{113}{64}\cos^2 \theta $? I have an example:
$$ \frac{49}{64}\cos^2 \theta + \cos^2 \theta = 1 $$
Then what happens next:
$$ \frac{113}{64}\cos^2 \theta = 1 $$
Where has the other cosine disappeared to? What operation happened here? Any hints please.

This is a simple use of the distributive law (Wikipedia link):
$$ac+bc=(a+b)c$$
In this situation,
$$\left(\frac{49}{64}\right)\cos^2(\theta)+\left(1\right)\cos^2(\theta)=\left(\frac{49}{64}+1\right)\cos^2(\theta)=\left(\frac{113}{64}\right)\cos^2(\theta)$$
