cos(arcsin(21/29))

解答

cos (arcsin (\frac{21}{29}))

\frac{20}{29}

十进制

0.68965 \dots

求解步骤

cos (arcsin (\frac{21}{29}))

使用三角恒等式改写:

cos (arcsin (\frac{21}{29})) = 1 - (\frac{21}{29})^{2}

利用以下特性:

cos (arcsin (x)) = 1 - x^{2}

= 1 - (\frac{21}{29})^{2}

= 1 - (\frac{21}{29})^{2}

化简

= \frac{20}{29}

3 (- 7 cos (7) + sin (7) + cos (1) - sin (1))

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sec (\frac{15}{12})

\frac{tan ( 8 2 ^{\circ} ) + tan ( 3 8 ^{\circ} )}{1 - tan ( 8 2 ^{\circ} ) tan ( 3 8 ^{\circ} )}

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