RICHIAMI DI TRIGONOMETRIA sen cos tg - Cartesio.dima.unige.it
RICHIAMI DI TRIGONOMETRIA sen cos tg - Cartesio.dima.unige.it
RICHIAMI DI TRIGONOMETRIA sen cos tg - Cartesio.dima.unige.it
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Angoli notevoli<br />
0 π<br />
<strong>RICHIAMI</strong> <strong>DI</strong> <strong>TRIGONOMETRIA</strong><br />
<strong>sen</strong> 0 0 1 –1<br />
<strong>cos</strong> 1 –1 0 0<br />
<strong>tg</strong> 0 0<br />
π<br />
2<br />
non<br />
defin<strong>it</strong>a<br />
3π<br />
2<br />
non<br />
defin<strong>it</strong>a<br />
π<br />
6<br />
1<br />
2<br />
3<br />
2<br />
π<br />
3<br />
3<br />
2<br />
1<br />
2<br />
π<br />
4<br />
2<br />
2<br />
2<br />
2<br />
3<br />
3 3 1<br />
Ricordiamo che le funzioni <strong>sen</strong>o, co<strong>sen</strong>o e tangente sono periodiche rispettivamente di periodo<br />
2 π, 2 π, π.<br />
Si ha sempre <strong>sen</strong> 2 α + <strong>cos</strong> 2 α = 1, da cui si ottiene <strong>tg</strong> 2 α + 1 =<br />
Angoli associati<br />
1<br />
<strong>cos</strong> 2<br />
<strong>sen</strong> (− α) = − <strong>sen</strong> α <strong>cos</strong> (− α) = <strong>cos</strong> α <strong>tg</strong> (− α) = - <strong>tg</strong> α<br />
<strong>sen</strong> (π + α) = − <strong>sen</strong> α <strong>cos</strong> (π + α) = − <strong>cos</strong> α <strong>tg</strong> (π + α) = <strong>tg</strong> α<br />
<strong>sen</strong> (π − α) = <strong>sen</strong> α <strong>cos</strong> (π − α) = − <strong>cos</strong> α <strong>tg</strong> (π − α) = − <strong>tg</strong> α<br />
<strong>sen</strong> ( π<br />
2<br />
<strong>sen</strong> ( π<br />
2<br />
+ α) = <strong>cos</strong> α <strong>cos</strong> (π<br />
2<br />
− α) = <strong>cos</strong> α <strong>cos</strong> (π<br />
2<br />
dove co<strong>tg</strong> α = 1<br />
<strong>tg</strong> α<br />
Addizione e sottrazione<br />
+ α) = − <strong>sen</strong> α <strong>tg</strong> (π<br />
2<br />
− α) = <strong>sen</strong> α <strong>tg</strong> (π<br />
2<br />
.<br />
+ α) = co<strong>tg</strong> α<br />
− α) = − co<strong>tg</strong> α<br />
<strong>cos</strong> (α + β) = <strong>cos</strong> α <strong>cos</strong> β − <strong>sen</strong> α <strong>sen</strong> β <strong>cos</strong> (α − β) = <strong>cos</strong> α <strong>cos</strong> β + <strong>sen</strong> α <strong>sen</strong> β<br />
<strong>sen</strong> (α + β) = <strong>sen</strong> α <strong>cos</strong> β + <strong>cos</strong> α <strong>sen</strong> β <strong>sen</strong> (α − β) = <strong>sen</strong> α <strong>cos</strong> β − <strong>cos</strong> α <strong>sen</strong> β<br />
<strong>tg</strong> (α + β) =<br />
<strong>tg</strong> α + <strong>tg</strong> β<br />
1 − <strong>tg</strong> α <strong>tg</strong> β<br />
<strong>tg</strong> (α − β) = <strong>tg</strong> α − <strong>tg</strong> β<br />
1 + <strong>tg</strong> α <strong>tg</strong> β
Duplicazione<br />
<strong>sen</strong> 2α = 2 <strong>sen</strong> α <strong>cos</strong> α <strong>cos</strong> 2α = <strong>cos</strong> 2 α − <strong>sen</strong> 2 α = 1 − 2 <strong>sen</strong> 2 α = 2 <strong>cos</strong> 2 α − 1<br />
<strong>tg</strong> 2α =<br />
Bisezione<br />
<strong>sen</strong> α<br />
2<br />
<strong>tg</strong> α<br />
2<br />
2 <strong>tg</strong> α<br />
1 − <strong>tg</strong> 2 α<br />
1 – <strong>cos</strong>α<br />
= ± 2 <strong>cos</strong> α<br />
2<br />
= ± 1 – <strong>cos</strong>α<br />
1 + <strong>cos</strong>α<br />
= 1 – <strong>cos</strong>α<br />
<strong>sen</strong>α =<br />
<strong>sen</strong>α<br />
1 + <strong>cos</strong>α<br />
(il segno si sceglie secondo il quadrante in cui si trova α<br />
2 ).<br />
Prostaferesi<br />
<strong>sen</strong> p + <strong>sen</strong> q = 2 <strong>sen</strong> p+q<br />
2<br />
<strong>cos</strong> p + <strong>cos</strong> q = 2 <strong>cos</strong> p+q<br />
2<br />
<strong>tg</strong> p + <strong>tg</strong> q =<br />
<strong>sen</strong> (p+q)<br />
<strong>cos</strong> p <strong>cos</strong> q<br />
Formule parametriche<br />
<strong>sen</strong> α =<br />
α<br />
2 <strong>tg</strong> 2<br />
α<br />
1 + <strong>tg</strong>2 2<br />
Equazioni trigonometriche<br />
<strong>cos</strong> p–q<br />
2<br />
<strong>cos</strong> p–q<br />
2<br />
<strong>cos</strong> α =<br />
= ± 1 + <strong>cos</strong>α<br />
2<br />
p–q<br />
<strong>sen</strong> p – <strong>sen</strong> q = 2 <strong>sen</strong> 2<br />
p+q<br />
<strong>cos</strong> p – <strong>cos</strong> q = – 2 <strong>sen</strong> 2<br />
<strong>sen</strong> (p–q)<br />
<strong>tg</strong> p – <strong>tg</strong> q = <strong>cos</strong> p <strong>cos</strong> q<br />
α<br />
1 − <strong>tg</strong>2 2<br />
α<br />
1 + <strong>tg</strong>2 2<br />
<strong>sen</strong> α = 0 α = κπ κ ∈ Z<br />
<strong>cos</strong> α = 0 α = π<br />
2<br />
+ κπ κ ∈ Z<br />
<strong>tg</strong> α = 0 α = κπ κ ∈ Z<br />
<strong>sen</strong> α = <strong>sen</strong> β α = (–1) κ β + κπ κ ∈ Z<br />
<strong>cos</strong> α = <strong>cos</strong> β α = ± β + 2κπ κ ∈ Z<br />
<strong>tg</strong> α = <strong>tg</strong> β α = β + κπ κ ∈ Z<br />
<strong>tg</strong> α =<br />
<strong>cos</strong> p+q<br />
2<br />
<strong>sen</strong> p–q<br />
2<br />
α<br />
2 <strong>tg</strong> 2<br />
α<br />
1 − <strong>tg</strong>2 2