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Question
sec2A – cosec2A = `(2sin^2"A" - 1)/(sin^2"A"*cos^2"A")` हे सिद्ध करा.
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Solution
डावी बाजू = sec2A – cosec2A
= `1/(cos^2"A") - 1/(sin^2"A")`
= `(sin^2"A" - cos^2"A")/(cos^2"A"*sin^2"A")`
= `(sin^2"A" - (1 - sin^2"A"))/(sin^2"A"*cos^2"A")` .....`[(because sin^2"A" + cos^2"A" = 1),(therefore 1 sin^2"A" = cos^2"A")]`
= `(sin^2"A" - 1 + sin^2"A")/(sin^2"A"*cos^2"A")`
= `(2sin^2"A" - 1)/(sin^2"A"*cos^2"A")`
= उजवी बाजू
∴ sec2A – cosec2A = `(2sin^2"A" - 1)/(sin^2"A"*cos^2"A")`
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`tanθ/(secθ - 1) = (tanθ + secθ + 1)/(tanθ + secθ - 1)`
`(sin θ - cos θ + 1)/(sin θ + cos θ - 1) = 1/(sec θ - tan θ)`
cos2θ . (1 + tan2θ) = 1 हे सिद्ध करण्यासाठी खालील कृती पूर्ण करा.
कृती: डावी बाजू = `square`
= `cos^2theta xx square` .........`[1 + tan^2theta = square]`
= `(cos theta xx square)^2`
= 12
= 1
= उजवी बाजू
जर tan θ = `7/24`, तर cos θ ची किंमत काढण्यासाठी खालील कृती पूर्ण करा.
कृती: sec2θ = 1 + `square` ......[त्रि. नित्य समीकरण]
sec2θ = 1 + `square^2`
sec2θ = 1 + `square/576`
sec2θ = `square/576`
sec θ = `square`
cos θ = `square` .......`[cos theta = 1/sectheta]`
cot θ + tan θ = cosec θ × sec θ, हे सिद्ध करण्यासाठी खालील कृती पूर्ण करा.
कृती:
डावी बाजू = `square`
= `square/sintheta + sintheta/costheta`
= `(cos^2theta + sin^2theta)/square`
= `1/(sintheta*costheta)` ......`[cos^2theta + sin^2theta = square]`
= `1/sintheta xx 1/square`
= `square`
= उजवी बाजू
`(tan(90 - theta) + cot(90 - theta))/("cosec" theta)` = sec θ हे सिद्ध करा.
`(1 + sintheta)/(1 - sin theta)` = (sec θ + tan θ)2 हे सिद्ध करा.
sec2θ – cos2θ = tan2θ + sin2θ हे सिद्ध करा.
`(cot "A" + "cosec A" - 1)/(cot"A" - "cosec A" + 1) = (1 + cos "A")/"sin A"` हे सिद्ध करा.
sin2θ + cos2θ ची किंमत काढा.
उकलः
Δ ABC मध्ये, ∠ABC = 90°, ∠C = θ°
AB2 + BC2 = `square` ...(पायथागोरसचे प्रमेय)
दोन्ही बाजूला AC2 ने भागून,
`"AB"^2/"AC"^2 + "BC"^2/"AC"^2 = "AC"^2/"AC"^2`
∴ `("AB"^2/"AC"^2) + ("BC"^2/"AC"^2) = 1`
परंतु `"AB"/"AC" = square "आणि" "BC"/"AC" = square`
∴ `sin^2 theta + cos^2 theta = square`
