You have the following expression:

To verify the identity, you have that the left side of the equation becomes:
(1 + cosx)(1 - cosx) = (1 - cos^2 x)
because of the product of an expression by its conjugate result in a difference of squares. Or simplfy by expanding the factors and simplying.
Next, you have:
1 - cos^2 x = sin^2 x
because the Pythagorean identity.
Then, the identity is verified.
Answer:
62
Step-by-step explanation:
26+36=x
x=62
3k+10=2k-21
move 2k to the other side
sign changes from +2k to -2k
3k-2k+10=2k-2k-21( combine like terms)
3k-2k+10= -21
k+10=-21
move +10 to the other side
k+10-10= -21-10
k= -21-10
answer:
k= -31
Honestly, the most intelligent solution would be to light the candle first, since it has a longer duration and then I can light the lamp, and then I can light the newspaper. Then, I will use the newspaper to light the fire.
Check the picture below
notice, using the 30-60-90 rule, since that triangle is a 30-60-90 triangle, we get 11 = 2x