Find the exact value. cos(2tan^-1_7/24)?

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Find the exact value. cos(2tan^-1_7/24)?

please help, thank you.

2007-12-05 04:27:06 · 2 answers · asked by weetereatter 2 in Science & Mathematics ➔ Mathematics

2 answers

let A = arctan(7/24)

tan A = 7/24
cos A = 24/25 ... since tanθ=y/x while cosθ=x/r
cos(2A) = 2cos²A - 1 ... use double angle formula.
= 2(24/25)² - 1
= 1152/625 - 1
= 527/625

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2007-12-05 04:39:07 · answer #1 · answered by Alam Ko Iyan 7 · 0⤊ 0⤋

= cos(2cos^-1 24/25)
= (24/25)^2 - (7/25)^2
= (576 -49)/625 = 527/625

2007-12-05 12:48:47 · answer #2 · answered by ironduke8159 7 · 0⤊ 0⤋