If cosec theta=2, show that cot theta+sin theta/1+cos theta=2
Answers
Trigonometry: Trigonometry is the study of angles and relations between angles and their sin, cos, tan, cosec, sec, cot ratios. There are many formulae for calculations:
• sin²A + cos²A = 1
• sec²A - tan²A = 1
• cosec²A - cot²A = 1
• sin2A = 2 sinA cosA
• cos2A = cos²A - sin²A
• tan2A = 2 tanA / (1 - tan²A)
• cosec(π/6) = 2
Proof:
Given,
cosecθ = 2
or, cosecθ = cosec(π/6)
Then θ = π/6
L.H.S. = cotθ + sinθ/(1 + cosθ)
= cot(π/6) + {sin(π/6)}/{1 + cos(π/6)}
= √3 + (1/2)/{1 + (√3)/2}
= √3 + 1/(2 + √3)
= (2√3 + 3 + 1)/(2 + √3)
= (4 + 2√3)/(2 + √3)
= 2 (2 + √3)/(2 + √3)
= 2 = R.H.S.
∴ cotθ + sinθ/(1 + cosθ) = 2, where cosecθ = 2
Hence proved.