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PRIYA SINGH

· started a discussion

· 1 Months ago

SECOND STEP ME sec^20-tan^2=1 ke formula ko break karke 1/4 ka value nikala gaya hai

Question:
If sec\(\theta\) + tan\(\theta\) = 4, (\(\theta\neq\) 90º), then the value of cos\(\theta\) is – 
Options:
A) 0
B) \(\cfrac{8}{17}\)
C) \(\cfrac{17}{8}\)
D) \(\cfrac{4}{5}\)
Solution:
Ans: (b) Sec\(\theta\) + tan\(\theta\)  = 4 

sec\(\theta\) - tan\(\theta\)  = \(\cfrac{1}{4}\)

2 sec\(\theta\) = 4 + \(\cfrac{1}{4} = \cfrac{17}{4}\)

sec \(\theta\)= \(\cfrac{17}{8}\)

cos\(\theta\) = \(\cfrac{8}{17}\)

Knowledge Expert

· commented

· 1 Months ago

Yes,

we have sec(theta)+tan(theta)=4

sec(theta)+tan(theta) * sec(theta)-tan(theta) / sec(theta)-tan(theta)=4

sec^2(theta)-tan^2(theta) / sec(theta)-tan(theta)=4

[Since,sec^2(theta)-tan^2(theta) = 1]

so, 1 / sec(theta)-tan(theta)=4

sec(theta)-tan(theta)=1/4

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