cos(A)= 5/8

解答

cos (A) = \frac{5}{8}

A = 0.89566 \dots + 2 πn, A = 2 π - 0.89566 \dots + 2 πn

度数

A = 51.31781 \dots^{\circ} + 36 0^{\circ} n, A = 308.68218 \dots^{\circ} + 36 0^{\circ} n

求解步骤

cos (A) = \frac{5}{8}

使用反三角函数性质

cos (A) = \frac{5}{8}

cos (A) = \frac{5}{8}

的通解

cos (x) = a \Rightarrow x = arccos (a) + 2 πn, x = 2 π - arccos (a) + 2 πn

A = arccos (\frac{5}{8}) + 2 πn, A = 2 π - arccos (\frac{5}{8}) + 2 πn

A = arccos (\frac{5}{8}) + 2 πn, A = 2 π - arccos (\frac{5}{8}) + 2 πn

以小数形式表示解

A = 0.89566 \dots + 2 πn, A = 2 π - 0.89566 \dots + 2 πn

sin (9 x + 40) = cos (- 5 x + 42)

sin^{2} (a) = - \frac{( 5 11 )}{( 18 )}

3.87 sin (\frac{2 π ( t + 101.75 )}{365}) + 11.7 = 14

2 sin (2 x) = 3, 0 \leq x \leq 2 π

cosh (2 x) + sinh^{2} (x) - 13 sinh (x) = - 3