Oblicz wartości pozostałych funkcji trynogometrycznych dla kąta o mierze < < wiedząc, że:
a) =
b) =
c) = 2
d) =
a)
=
sin²α + cos²α = 1
sin²α = 1 - cos²α
sinα = √ 1 - cos²α = √ 1 - (¹/₃)² = √ ⁹/₉ - ¹/₉ = √⁸/₉ = (√8)/(√9) = ( √4·√2 ) / 3 = 2√2 / 3
tgα = sinα / cosα = ( 2√2 / 3 ) ÷ ⅓ = ( 2√2 / 3 ) · 3 = 2√2
ctgα = cosα / sinα = ⅓ / ( 2√2 / 3 ) = ⅓ · ( 3 / 2√2 ) = ( 1 / 2√2 ) · (√2/√2) = √2/4
b)
cos²α = 1 - sin²α
cosα = √ 1 - sin²α = √1 - ³/₅ = √ ⁵/₅ - ³/₅ = √ ²/₅ · (√5/√5) = √10 / 5
tgα = sinα / cosα = ³/₅ ÷ ( √10 / 5 ) = ³/₅ · 5 / √10 = ³/ √10 · (√10 / √10) = 3√10 / 10
ctgα = cosα / sinα = (3√10 / 10) ÷ ³/₅ = (3√10 / 10) · ⁵/₃ = 3√10 / 6 = √10 / 2
c)
= 2
ctgα = 1 / tgα = ½
sinα / cosα = 2
sinα = 2 cosα
(2 cosα)² = 1 - cos²α
4cos²α + cos²α = 1
4 cos²α = 1 /:4
cos²α = ¹/₄
cosα = √¹/₄ = ½
sinα = 2 cosα = 2 · ½ = 1
d)
tgα = 1/ctgα = 1 ÷ ²/₃ = 1 · ³/₂ = ³/₂
cosα/ sinα = ²/₃
cosα= ²/₃ sinα
sin²α = 1 - (²/₃ sinα)²
sin²α = 1 - ⁴/₉ sin²α
sin²α + ⁴/₉ sin²α = 1
¹³/₉ sin²α= 1 / · ⁹/₁₃
sin²α = ⁹/₁₃
sinα = √⁹/₁₃ = √9/√13 · (√13/√13) = 3√13 ÷ 13
cosα= ²/₃ sinα = ²/₃ · 3√13 ÷ 13 = 2√13 ÷ 13
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a)
=
sin²α + cos²α = 1
sin²α = 1 - cos²α
sinα = √ 1 - cos²α = √ 1 - (¹/₃)² = √ ⁹/₉ - ¹/₉ = √⁸/₉ = (√8)/(√9) = ( √4·√2 ) / 3 = 2√2 / 3
tgα = sinα / cosα = ( 2√2 / 3 ) ÷ ⅓ = ( 2√2 / 3 ) · 3 = 2√2
ctgα = cosα / sinα = ⅓ / ( 2√2 / 3 ) = ⅓ · ( 3 / 2√2 ) = ( 1 / 2√2 ) · (√2/√2) = √2/4
b)
=
sin²α + cos²α = 1
cos²α = 1 - sin²α
cosα = √ 1 - sin²α = √1 - ³/₅ = √ ⁵/₅ - ³/₅ = √ ²/₅ · (√5/√5) = √10 / 5
tgα = sinα / cosα = ³/₅ ÷ ( √10 / 5 ) = ³/₅ · 5 / √10 = ³/ √10 · (√10 / √10) = 3√10 / 10
ctgα = cosα / sinα = (3√10 / 10) ÷ ³/₅ = (3√10 / 10) · ⁵/₃ = 3√10 / 6 = √10 / 2
c)
= 2
ctgα = 1 / tgα = ½
sinα / cosα = 2
sinα = 2 cosα
sin²α + cos²α = 1
sin²α = 1 - cos²α
(2 cosα)² = 1 - cos²α
4cos²α + cos²α = 1
4 cos²α = 1 /:4
cos²α = ¹/₄
cosα = √¹/₄ = ½
sinα = 2 cosα = 2 · ½ = 1
d)
=
tgα = 1/ctgα = 1 ÷ ²/₃ = 1 · ³/₂ = ³/₂
cosα/ sinα = ²/₃
cosα= ²/₃ sinα
sin²α + cos²α = 1
sin²α = 1 - cos²α
sin²α = 1 - (²/₃ sinα)²
sin²α = 1 - ⁴/₉ sin²α
sin²α + ⁴/₉ sin²α = 1
¹³/₉ sin²α= 1 / · ⁹/₁₃
sin²α = ⁹/₁₃
sinα = √⁹/₁₃ = √9/√13 · (√13/√13) = 3√13 ÷ 13
cosα= ²/₃ sinα = ²/₃ · 3√13 ÷ 13 = 2√13 ÷ 13