how to use the inverse functions without a calculator

[abel muroi]

I was given a problem that asked me to find the angle in degrees of (theta)

cos(theta) = 1/2

i am used to dividing the sides and using the inverse function in my calculator to get the degrees but im wondering if there's a way to use the inverse functions without a calculator?

 

[Deleted member 4993]

I was given a problem that asked me to find the angle in degrees of (theta)

cos(theta) = 1/2

i am used to dividing the sides and using the inverse function in my calculator to get the degrees but im wondering if there's a way to use the inverse functions without a calculator?

Remembering ....

cos(±π/3 ± 2*n*π) = 1/2

 

[abel muroi]

Remembering ....

cos(±π/3 ± 2*n*π) = 1/2

I see, but can you explain how that formula works?

 

[stapel]

I see, but can you explain how that formula works?

Periodic waves have periods, over which they repeat their values. The period for sine and cosine waves is \(\displaystyle 2\pi.\,\)

Has your class not yet covered basic reference-angle values?