Question
If 2cos²A + 3sin²A = 13/5, then find the value of (sec²A
- 1)Solution
2cos²A + 3sin²A = 13/5
Or, -1cos²A + 3(cos²A + sin²A) = 13/5
Or, -cos²A + 3 = 13/5
Or, -cos²A = 13/5 - 3 = -2/5 => cos²A = 2/5
So, sec²A = 1 / (2/5) = 5/2
Required value = 5/2 - 1 = 3/2
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