Simplify the expression by using a double-angle formula.
cos-39°– sin²39

cos 78⁰.

Step-by-step explanation:

Use cos 2A = cos^2 A - sin^2 A

so cos^2 39 - sin^2 39 = cos (2*39) = cos 78.

logv3(x+2)=1

rewrite in exponential form:

logb(x) = y is equal to b^y =x

b = 3, y = 1

now solve for x:

3^1 = x+2)

x = 3-2

x = 1

see the picture for the graph.

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