If sin (2x )= cos (x+15) and 0< x ≤90, what is the value of x?

because sin(2x)=cos(x+15) is true x+15=90-2x

We can say this because assume a right triangle, there are 2 different angles, and the sin of one = the cos of the other.

Now solving this 3x=75

x=25 degrees

Hope it helps!

step-by-step explanation: a reaction is first order. if the initial reactant concentration is 0.0200 m, and 25.0 days later the concentration is 6.25 x 10-4 m, then its half-life is: