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人気のある三角関数 >

証明する tan(pi/4-t)=(1-tan(t))/(1+tan(t))

解

証明する

tan (\frac{π}{4} - t) = \frac{1 - tan ( t )}{1 + tan ( t )}

解

真

解答ステップ

tan (\frac{π}{4} - t) = \frac{1 - tan ( t )}{1 + tan ( t )}

左側を操作する

tan (\frac{π}{4} - t)

三角関数の公式を使用して書き換える

tan (\frac{π}{4} - t)

基本的な三角関数の公式を使用する:

tan (x) = \frac{sin ( x )}{cos ( x )}

= \frac{sin ( \frac{π}{4} - t )}{cos ( \frac{π}{4} - t )}

角の差の公式を使用する:

sin (s - t) = sin (s) cos (t) - cos (s) sin (t)

= \frac{sin ( \frac{π}{4} ) cos ( t ) - cos ( \frac{π}{4} ) sin ( t )}{cos ( \frac{π}{4} - t )}

角の差の公式を使用する:

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

= \frac{sin ( \frac{π}{4} ) cos ( t ) - cos ( \frac{π}{4} ) sin ( t )}{cos ( \frac{π}{4} ) cos ( t ) + sin ( \frac{π}{4} ) sin ( t )}

簡素化

\frac{sin ( \frac{π}{4} ) cos ( t ) - cos ( \frac{π}{4} ) sin ( t )}{cos ( \frac{π}{4} ) cos ( t ) + sin ( \frac{π}{4} ) sin ( t )} : \frac{cos ( t ) - sin ( t )}{cos ( t ) + sin ( t )}

\frac{sin ( \frac{π}{4} ) cos ( t ) - cos ( \frac{π}{4} ) sin ( t )}{cos ( \frac{π}{4} ) cos ( t ) + sin ( \frac{π}{4} ) sin ( t )}

sin (\frac{π}{4}) cos (t) - cos (\frac{π}{4}) sin (t) = \frac{2}{2} cos (t) - \frac{2}{2} sin (t)

sin (\frac{π}{4}) cos (t) - cos (\frac{π}{4}) sin (t)

簡素化

sin (\frac{π}{4}) : \frac{2}{2}

sin (\frac{π}{4})

次の自明恒等式を使用する:

sin (\frac{π}{4}) = \frac{2}{2}

sin (x)

2 πn

循環を含む周期性テーブル:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} 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}

= \frac{2}{2} cos (t) - cos (\frac{π}{4}) sin (t)

簡素化

cos (\frac{π}{4}) : \frac{2}{2}

cos (\frac{π}{4})

次の自明恒等式を使用する:

cos (\frac{π}{4}) = \frac{2}{2}

cos (x)

2 πn

循環を含む周期性テーブル:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} 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}

= \frac{2}{2} cos (t) - \frac{2}{2} sin (t)

= \frac{\frac{2}{2} cos ( t ) - \frac{2}{2} sin ( t )}{cos ( \frac{π}{4} ) cos ( t ) + sin ( \frac{π}{4} ) sin ( t )}

cos (\frac{π}{4}) cos (t) + sin (\frac{π}{4}) sin (t) = \frac{2}{2} cos (t) + \frac{2}{2} sin (t)

cos (\frac{π}{4}) cos (t) + sin (\frac{π}{4}) sin (t)

簡素化

cos (\frac{π}{4}) : \frac{2}{2}

cos (\frac{π}{4})

次の自明恒等式を使用する:

cos (\frac{π}{4}) = \frac{2}{2}

cos (x)

2 πn

循環を含む周期性テーブル:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} 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}

= \frac{2}{2} cos (t) + sin (\frac{π}{4}) sin (t)

簡素化

sin (\frac{π}{4}) : \frac{2}{2}

sin (\frac{π}{4})

次の自明恒等式を使用する:

sin (\frac{π}{4}) = \frac{2}{2}

sin (x)

2 πn

循環を含む周期性テーブル:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} sin (x) 0 \frac{1}{2} \frac{2}{2} \frac{3}{2} 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} 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}

= \frac{2}{2} cos (t) + \frac{2}{2} sin (t)

= \frac{\frac{2}{2} cos ( t ) - \frac{2}{2} sin ( t )}{\frac{2}{2} cos ( t ) + \frac{2}{2} sin ( t )}

乗じる

\frac{2}{2} cos (t) : \frac{2 cos ( t )}{2}

\frac{2}{2} cos (t)

分数を乗じる:

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

= \frac{2 cos ( t )}{2}

= \frac{\frac{2}{2} cos ( t ) - \frac{2}{2} sin ( t )}{\frac{2 c o s ( t )}{2} + \frac{2}{2} sin ( t )}

乗じる

\frac{2}{2} sin (t) : \frac{2 sin ( t )}{2}

\frac{2}{2} sin (t)

分数を乗じる:

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

= \frac{2 sin ( t )}{2}

= \frac{\frac{2}{2} cos ( t ) - \frac{2}{2} sin ( t )}{\frac{2 c o s ( t )}{2} + \frac{2 s i n ( t )}{2}}

乗じる

\frac{2}{2} cos (t) : \frac{2 cos ( t )}{2}

\frac{2}{2} cos (t)

分数を乗じる:

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

= \frac{2 cos ( t )}{2}

= \frac{\frac{2 c o s ( t )}{2} - \frac{2}{2} sin ( t )}{\frac{2 c o s ( t )}{2} + \frac{2 s i n ( t )}{2}}

乗じる

\frac{2}{2} sin (t) : \frac{2 sin ( t )}{2}

\frac{2}{2} sin (t)

分数を乗じる:

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

= \frac{2 sin ( t )}{2}

= \frac{\frac{2 c o s ( t )}{2} - \frac{2 s i n ( t )}{2}}{\frac{2 c o s ( t )}{2} + \frac{2 s i n ( t )}{2}}

分数を組み合わせる

\frac{2 cos ( t )}{2} + \frac{2 sin ( t )}{2} : \frac{2 cos ( t ) + 2 sin ( t )}{2}

規則を適用

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

= \frac{2 cos ( t ) + 2 sin ( t )}{2}

= \frac{\frac{2 c o s ( t )}{2} - \frac{2 s i n ( t )}{2}}{\frac{2 c o s ( t ) + 2 s i n ( t )}{2}}

分数を組み合わせる

\frac{2 cos ( t )}{2} - \frac{2 sin ( t )}{2} : \frac{2 cos ( t ) - 2 sin ( t )}{2}

規則を適用

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

= \frac{2 cos ( t ) - 2 sin ( t )}{2}

= \frac{\frac{2 c o s ( t ) - 2 s i n ( t )}{2}}{\frac{2 c o s ( t ) + 2 s i n ( t )}{2}}

分数を割る:

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

= \frac{( 2 cos ( t ) - 2 sin ( t ) ) \cdot 2}{2 ( 2 cos ( t ) + 2 sin ( t ) )}

共通因数を約分する:

2

= \frac{2 cos ( t ) - 2 sin ( t )}{2 cos ( t ) + 2 sin ( t )}

共通項をくくり出す

2

= \frac{2 ( cos ( t ) - sin ( t ) )}{2 cos ( t ) + 2 sin ( t )}

共通項をくくり出す

2

= \frac{2 ( cos ( t ) - sin ( t ) )}{2 ( cos ( t ) + sin ( t ) )}

共通因数を約分する:

2

= \frac{cos ( t ) - sin ( t )}{cos ( t ) + sin ( t )}

= \frac{cos ( t ) - sin ( t )}{cos ( t ) + sin ( t )}

= \frac{cos ( t ) - sin ( t )}{cos ( t ) + sin ( t )}

右側を操作する

\frac{1 - tan ( t )}{1 + tan ( t )}

サイン, コサインで表わす

\frac{1 - tan ( t )}{1 + tan ( t )}

基本的な三角関数の公式を使用する:

tan (x) = \frac{sin ( x )}{cos ( x )}

= \frac{1 - \frac{s i n ( t )}{c o s ( t )}}{1 + \frac{s i n ( t )}{c o s ( t )}}

簡素化

\frac{1 - \frac{s i n ( t )}{c o s ( t )}}{1 + \frac{s i n ( t )}{c o s ( t )}} : \frac{cos ( t ) - sin ( t )}{cos ( t ) + sin ( t )}

\frac{1 - \frac{s i n ( t )}{c o s ( t )}}{1 + \frac{s i n ( t )}{c o s ( t )}}

結合

1 + \frac{sin ( t )}{cos ( t )} : \frac{cos ( t ) + sin ( t )}{cos ( t )}

1 + \frac{sin ( t )}{cos ( t )}

元を分数に変換する:

1 = \frac{1 cos ( t )}{cos ( t )}

= \frac{1 \cdot cos ( t )}{cos ( t )} + \frac{sin ( t )}{cos ( t )}

分母が等しいので, 分数を組み合わせる:

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

= \frac{1 \cdot cos ( t ) + sin ( t )}{cos ( t )}

乗算:

1 \cdot cos (t) = cos (t)

= \frac{cos ( t ) + sin ( t )}{cos ( t )}

= \frac{1 - \frac{s i n ( t )}{c o s ( t )}}{\frac{c o s ( t ) + s i n ( t )}{c o s ( t )}}

結合

1 - \frac{sin ( t )}{cos ( t )} : \frac{cos ( t ) - sin ( t )}{cos ( t )}

1 - \frac{sin ( t )}{cos ( t )}

元を分数に変換する:

1 = \frac{1 cos ( t )}{cos ( t )}

= \frac{1 \cdot cos ( t )}{cos ( t )} - \frac{sin ( t )}{cos ( t )}

分母が等しいので, 分数を組み合わせる:

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

= \frac{1 \cdot cos ( t ) - sin ( t )}{cos ( t )}

乗算:

1 \cdot cos (t) = cos (t)

= \frac{cos ( t ) - sin ( t )}{cos ( t )}

= \frac{\frac{c o s ( t ) - s i n ( t )}{c o s ( t )}}{\frac{c o s ( t ) + s i n ( t )}{c o s ( t )}}

分数を割る:

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

= \frac{( cos ( t ) - sin ( t ) ) cos ( t )}{cos ( t ) ( cos ( t ) + sin ( t ) )}

共通因数を約分する:

cos (t)

= \frac{cos ( t ) - sin ( t )}{cos ( t ) + sin ( t )}

= \frac{cos ( t ) - sin ( t )}{cos ( t ) + sin ( t )}

= \frac{cos ( t ) - sin ( t )}{cos ( t ) + sin ( t )}

両辺を同じ形式にできることを証明した

\Rightarrow 真

人気の例

証明する-tan(x)=tan(-x)

p ro v e - tan (x) = tan (- x)

証明する sin(3θ)=3cos^2(θ)sin(θ)-sin^3(θ)

p ro v e sin (3 θ) = 3 cos^{2} (θ) sin (θ) - sin^{3} (θ)

証明する sin(x)sin(3x)=4sin(x)cos^2(x)

p ro v e sin (x) sin (3 x) = 4 sin (x) cos^{2} (x)

証明する sec(pi/2-t)=csc(t)

p ro v e sec (\frac{π}{2} - t) = csc (t)

証明する sin(3u)=sin(u)(3-4sin^2(u))

p ro v e sin (3 u) = sin (u) (3 - 4 sin^{2} (u))