sin 0 = 2√2/3 find cos 0.?
0 is an acute angle and sin 0 is given. Use the Pythagorean identity sin^2 0 + cos^2 0 = 1 to find cos 0.
Problem:
sin 0 = 2√2/3
Please help, thanks. The "0" also has a line through it, I forgot what this means.
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Answers & Comments
It's not a 0. It's a Greek letter called theta.
I think you meant sin theta = sqrt(2/3)
If so, sin^2 theta = 2/3
so cos^2 theta = 1 - 2/3 = 1/3
cos theta = +/-sqrt(1/3)
cos^2A=1-sin^2A
cos^2A=1-[2.sqrt(2)/3]^2 = 1-(4.2)/9
cos^2A = 1-8/9
cos^2A = (8-9)/9
cos^2A = 1/9
cosA = +/-sqtr(1/9)
cosA = +/-(1/3)
since A is acute
cosA = 1/3