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受欢迎的三角函数 >

cos^2(165)-sin^2(165)

解答

cos^{2} (16 5^{\circ}) - sin^{2} (16 5^{\circ})

解答

1 - \frac{2 - 3}{2}

+1

十进制

0.86602 \dots

求解步骤

cos^{2} (16 5^{\circ}) - sin^{2} (16 5^{\circ})

使用三角恒等式改写:

cos^{2} (16 5^{\circ}) = 1 - sin^{2} (16 5^{\circ})

cos^{2} (16 5^{\circ})

使用毕达哥拉斯恒等式:

cos^{2} (x) + sin^{2} (x) = 1

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

= 1 - sin^{2} (16 5^{\circ})

= 1 - sin^{2} (16 5^{\circ}) - sin^{2} (16 5^{\circ})

化简

= 1 - 2 sin^{2} (16 5^{\circ})

使用三角恒等式改写:

sin (16 5^{\circ}) = \frac{6 - 2}{4}

sin (16 5^{\circ})

使用三角恒等式改写:

sin (13 5^{\circ}) cos (3 0^{\circ}) + cos (13 5^{\circ}) sin (3 0^{\circ})

sin (16 5^{\circ})

将

sin (16 5^{\circ})

写为

sin (13 5^{\circ} + 3 0^{\circ})

= sin (13 5^{\circ} + 3 0^{\circ})

使用角和恒等式:

sin (s + t) = sin (s) cos (t) + cos (s) sin (t)

= sin (13 5^{\circ}) cos (3 0^{\circ}) + cos (13 5^{\circ}) sin (3 0^{\circ})

= sin (13 5^{\circ}) cos (3 0^{\circ}) + cos (13 5^{\circ}) sin (3 0^{\circ})

使用以下普通恒等式:

sin (13 5^{\circ}) = \frac{2}{2}

sin (13 5^{\circ})

sin (x)

周期表（周期为

36 0^{\circ} n

"）：

x 0 3 0^{\circ} 4 5^{\circ} 6 0^{\circ} 9 0^{\circ} 12 0^{\circ} 13 5^{\circ} 15 0^{\circ} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} x 18 0^{\circ} 21 0^{\circ} 22 5^{\circ} 24 0^{\circ} 27 0^{\circ} 30 0^{\circ} 31 5^{\circ} 33 0^{\circ} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

= \frac{2}{2}

使用以下普通恒等式:

cos (3 0^{\circ}) = \frac{3}{2}

cos (3 0^{\circ})

cos (x)

周期表（周期为

36 0^{\circ} n

）：

x 0 3 0^{\circ} 4 5^{\circ} 6 0^{\circ} 9 0^{\circ} 12 0^{\circ} 13 5^{\circ} 15 0^{\circ} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x 18 0^{\circ} 21 0^{\circ} 22 5^{\circ} 24 0^{\circ} 27 0^{\circ} 30 0^{\circ} 31 5^{\circ} 33 0^{\circ} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

= \frac{3}{2}

使用以下普通恒等式:

cos (13 5^{\circ}) = - \frac{2}{2}

cos (13 5^{\circ})

cos (x)

周期表（周期为

36 0^{\circ} n

）：

x 0 3 0^{\circ} 4 5^{\circ} 6 0^{\circ} 9 0^{\circ} 12 0^{\circ} 13 5^{\circ} 15 0^{\circ} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x 18 0^{\circ} 21 0^{\circ} 22 5^{\circ} 24 0^{\circ} 27 0^{\circ} 30 0^{\circ} 31 5^{\circ} 33 0^{\circ} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

= - \frac{2}{2}

使用以下普通恒等式:

sin (3 0^{\circ}) = \frac{1}{2}

sin (3 0^{\circ})

sin (x)

周期表（周期为

36 0^{\circ} n

"）：

x 0 3 0^{\circ} 4 5^{\circ} 6 0^{\circ} 9 0^{\circ} 12 0^{\circ} 13 5^{\circ} 15 0^{\circ} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} x 18 0^{\circ} 21 0^{\circ} 22 5^{\circ} 24 0^{\circ} 27 0^{\circ} 30 0^{\circ} 31 5^{\circ} 33 0^{\circ} sin (x) 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2}

= \frac{1}{2}

= \frac{2}{2} \cdot \frac{3}{2} + (- \frac{2}{2}) \frac{1}{2}

化简

\frac{2}{2} \cdot \frac{3}{2} + (- \frac{2}{2}) \frac{1}{2} : \frac{6 - 2}{4}

\frac{2}{2} \cdot \frac{3}{2} + (- \frac{2}{2}) \frac{1}{2}

去除括号:

(- a) = - a

= \frac{2}{2} \cdot \frac{3}{2} - \frac{2}{2} \cdot \frac{1}{2}

\frac{2}{2} \cdot \frac{3}{2} = \frac{6}{4}

\frac{2}{2} \cdot \frac{3}{2}

分式相乘:

\frac{a}{b} \cdot \frac{c}{d} = \frac{a \cdot c}{b \cdot d}

= \frac{2 3}{2 \cdot 2}

数字相乘:

2 \cdot 2 = 4

= \frac{2 3}{4}

化简

23 : 6

23

使用根式运算法则:

a b = a \cdot b

23 = 2 \cdot 3

= 2 \cdot 3

数字相乘:

2 \cdot 3 = 6

= 6

= \frac{6}{4}

\frac{2}{2} \cdot \frac{1}{2} = \frac{2}{4}

\frac{2}{2} \cdot \frac{1}{2}

分式相乘:

\frac{a}{b} \cdot \frac{c}{d} = \frac{a \cdot c}{b \cdot d}

= \frac{2 \cdot 1}{2 \cdot 2}

乘以:

2 \cdot 1 = 2

= \frac{2}{2 \cdot 2}

数字相乘:

2 \cdot 2 = 4

= \frac{2}{4}

= \frac{6}{4} - \frac{2}{4}

使用法则

\frac{a}{c} \pm \frac{b}{c} = \frac{a \pm b}{c}

= \frac{6 - 2}{4}

= \frac{6 - 2}{4}

= 1 - 2 (\frac{6 - 2}{4})^{2}

化简

1 - 2 (\frac{6 - 2}{4})^{2} : 1 - \frac{2 - 3}{2}

1 - 2 (\frac{6 - 2}{4})^{2}

2 (\frac{6 - 2}{4})^{2} = \frac{2 - 3}{2}

2 (\frac{6 - 2}{4})^{2}

(\frac{6 - 2}{4})^{2} = \frac{2 - 3}{4}

(\frac{6 - 2}{4})^{2}

使用指数法则:

(\frac{a}{b})^{c} = \frac{a ^{c}}{b ^{c}}

= \frac{( 6 - 2 ) ^{2}}{4 ^{2}}

(6 - 2)^{2} = 8 - 43

(6 - 2)^{2}

使用完全平方公式:

(a - b)^{2} = a^{2} - 2 ab + b^{2}

a = 6, b = 2

= (6)^{2} - 262 + (2)^{2}

化简

(6)^{2} - 262 + (2)^{2} : 8 - 43

(6)^{2} - 262 + (2)^{2}

(6)^{2} = 6

(6)^{2}

使用根式运算法则:

a = a^{\frac{1}{2}}

= (6^{\frac{1}{2}})^{2}

使用指数法则:

(a^{b})^{c} = a^{b c}

= 6^{\frac{1}{2} \cdot 2}

\frac{1}{2} \cdot 2 = 1

\frac{1}{2} \cdot 2

分式相乘:

a \cdot \frac{b}{c} = \frac{a \cdot b}{c}

= \frac{1 \cdot 2}{2}

约分:

2

= 1

= 6

262 = 43

262

分解整数

6 = 2 \cdot 3

= 2 2 \cdot 3 2

使用根式运算法则:

n ab = n a n b

2 \cdot 3 = 23

= 2232

使用根式运算法则:

a a = a

22 = 2

= 2 \cdot 23

数字相乘:

2 \cdot 2 = 4

= 43

(2)^{2} = 2

(2)^{2}

使用根式运算法则:

a = a^{\frac{1}{2}}

= (2^{\frac{1}{2}})^{2}

使用指数法则:

(a^{b})^{c} = a^{b c}

= 2^{\frac{1}{2} \cdot 2}

\frac{1}{2} \cdot 2 = 1

\frac{1}{2} \cdot 2

分式相乘:

a \cdot \frac{b}{c} = \frac{a \cdot b}{c}

= \frac{1 \cdot 2}{2}

约分:

2

= 1

= 2

= 6 - 43 + 2

数字相加:

6 + 2 = 8

= 8 - 43

= 8 - 43

= \frac{8 - 4 3}{4 ^{2}}

分解

8 - 43 : 4 (2 - 3)

8 - 43

改写为

= 4 \cdot 2 - 43

因式分解出通项

4

= 4 (2 - 3)

= \frac{4 ( 2 - 3 )}{4 ^{2}}

约分:

4

= \frac{2 - 3}{4}

= 2 \cdot \frac{2 - 3}{4}

分式相乘:

a \cdot \frac{b}{c} = \frac{a \cdot b}{c}

= \frac{( 2 - 3 ) \cdot 2}{4}

约分:

2

= \frac{2 - 3}{2}

= 1 - \frac{2 - 3}{2}

= 1 - \frac{2 - 3}{2}

流行的例子

15 \cdot sin (6 0^{\circ})

sec(arccos(-(sqrt(2))/2))

sec (arccos (- \frac{2}{2}))

sin (π \cdot 1)

sin (0.05)

cos^2(pi/(12))-cos^2((5pi)/(12))

cos^{2} (\frac{π}{12}) - cos^{2} (\frac{5 π}{12})