If Tan A/2 and Tan B/2 are the roots of the equation 8x^2 – 26x +15 = 0 then cos(A+B) =?
If Tan A/2 and Tan B/2 are the roots of the equation 8x^2 – 26x +15 = 0 then cos(A+B) =?
Samaira Shah , 8 Years ago
Grade 11
Trigonometry> If Tan A/2 and Tan B/2 are the roots of t...
1 Answers
Arun
Dear student
tan A/2 + tan B/2 = 26/8 = 13/4
tan A/2 * tanB/2 = 15/8
Thus tan(A+B/2) = -26/7 (from formula)
Now
Cos(A+ B) = [1 - tan²(A+B/2)] /[1 + tan² (A+B/2)]
Cos (A+B) = -627/725
Regards
Arun (askIITians forum expert)
Approved Last Activity: 8 Years ago
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