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SecA+tanA=1.5 then find the value of sinA?
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SecA+tanA=1.5 then find the value of sinA?
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SecA+tanA=1.5 then find the value of sinA?
Solution:


Given:

SecA tanA=1.5


To find:

The value of sinA


Solution Steps:


Recall the trigonometric identities:



  • SecA = 1/CosA

  • TanA = SinA/CosA



Substituting the above identities in SecA TanA = 1.5, we get:



  • 1/CosA * SinA/CosA = 1.5

  • SinA/Cos²A = 1.5

  • SinA = 1.5 Cos²A



Recall the trigonometric identity:



  • Sin²A + Cos²A = 1

  • Sin²A = 1 - Cos²A



Substituting the value of SinA in the above identity, we get:



  • (1.5 Cos²A)² + Cos²A = 1

  • 2.25 Cos⁴A + Cos²A - 1 = 0



Let's substitute Cos²A as x:



  • 2.25x² + x - 1 = 0



Using the quadratic formula, we get:



  • x = (-b ± √(b² - 4ac))/2a

  • x = (-1 ± √(1 + 9))/4.5

  • x = (-1 ± √10)/4.5



As Cos²A cannot be negative, we take the positive root:



  • Cos²A = (-1 + √10)/4.5



Substituting this value in SinA = 1.5 Cos²A, we get:



  • SinA = 1.5 * (-1 + √10)/4.5

  • SinA = (-1 + √10)/9



Answer:

The value of sinA is (-1 + √10)/9.
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