maths
posted by jack on .
what's the value of A if cot^A(1  3 sec A + 2 sec^2 A)=1 and A>90 degrees.

I assume you mean
cot^2 A(1  3 sec A + 2 sec^2 A)=1
If so, then
1  3 sec A + 2 sec^2 A = tan^2 A
sec^2 A  3sec A + 2
(secA1)(secA2) = 0
secA=1 so A=0
secA=2 so A=π/3 or 5π/3
Looks like 5π/3 is the only solution > π/2
Check:
cot^2 5π/3 = 1/3
1  3 sec 5π/3 + 2 sec^2 5π/3 = 16+8 = 3