8. find the period and amplitude of the function. y=5cos2theta period: pi, radians; amplitude: 2.5 period pi, radians; amplitude: 5 period 2pi, radians; amplitude 2.5 period 2pi, radians; amplitude 5 if anyone knows the rest of the test that would be amazing for this 18 question test.

The general equation of the cosine function is
y = a cos nθ
where a is the amplitude 
And n = 2π/period

by comparing the general equation with the given equation which is 
Y = 5 cos 2θ
∴ a = 5  and   n = 2
∴ period = 2π/n = 2π/2 = π
∴ The amplitude = 5   and  the period = π

So, the correct answer is the second option

Period pi, radians; amplitude: 5

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