Hi,
We know that:
a² -- b² = (a -- b)(a + b).
With a = x, and b = 4, we have:
x² -- 16 = x² -- 4² = (x -- 4)(x + 4).
As simple as that. Have you understood ?
Green eyes.
Answer: look at the picture
Step-by-step explanation: Hope this help :D
we are given

we have to find theta
so, firstly we can write sin in terms of cos

now, we can set it equal

Since, both sides are cos
so, we can set angles equal

now, we can solve for theta
we get
..............Answer
9 and 3. Because 9 is a composite number (3*3 = 9) and 3 is a composite number (1*3 = 3).