InterviewSolution
Saved Bookmarks
| 1. |
\(\frac{{\sqrt {\ cosec x - 1} }}{{\sqrt {\ cosec x + 1} }}\) is equal to:1. \(\tan x - \sec x\)2. \(\sec x.\tan x\)3. \(\tan x + \sec x\)4. \(\sec x - \tan x\) |
|
Answer» Correct Answer - Option 4 : \(\sec x - \tan x\) Given: √(cosecx – 1)/√(cosecx + 1) Trigonometry identities used: sin2x + cos2x = 1 Formula used: a2 – b2 = (a + b) (a – b) Calculation: √(cosecx – 1)/√(cosecx + 1) (Here cosecx = 1/sinx √[(1/sinx) – 1]/√[(1/sinx) + 1] = √(1 – sinx)/√(1 + sinx) Rationalization = [√(1 – sinx)/√(1 + sinx)] × [√(1 – sinx)/√(1 – sinx)] = √(1 – sinx)2/√(1 + sinx) (1 – sinx) Here a2 – b2 = (a + b) (a – b) = (1 – sinx)/√(1 – sin2x) Here 1 – sin2x = cos2x = (1 – sinx)/√cos2x = (1 – sinx)/cosx = (1/cosx) – (sinx/cosx) Here 1/cosx = secx, sinx/cosx = tanx = secx – tanx |
|