Question 623387
secA+tanA= 4, then find sinA
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secA+tanA= 4
1/cos + sin/cos = 4
{{{sin(A) + 1 = 4cos(A) = 4*sqrt(1 - sin^2(A))}}}
Square both sides
sin^2 + 2sin + 1 = 16 - 16sin^2
17sin^2 + 2sin - 15 = 0
Sub x for sin(A)
*[invoke solve_quadratic_equation 17,2,-15]
sin = -1
The -1 solution can't be used - the secant is undefined.
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sin =~ 0.882353