       Re: Simple problem for math wiz

• To: mathgroup at christensen.cybernetics.net
• Subject: [mg1767] Re: [mg1685] Simple problem for math wiz
• From: Allan Hayes <hay at haystack.demon.co.uk>
• Date: Wed, 26 Jul 1995 00:53:46 -0400

```REVEAL <nomail at me.net> in
[mg1685] Simple problem for math wiz

> Anyone here know how to find the solution set to: sin^2x+sinx-1=0
? > the trick, that is?
> (limited to trig & algebra)

Solve[Sin[x]^2 + Sin[x] - 1 == 0,x]
Solve::ifun: Warning: Inverse functions are being used by
Solve, so some solutions may not be found.

-1 - Sqrt                 -1 + Sqrt
{{x -> ArcSin[------------]}, {x -> ArcSin[------------]}}
2                            2

Although, as Porfirio Beltran observed in [mg1708],

Solve[Sin[x]^2 + Sin[x] - 1 == 0]
-1 - Sqrt              -1 + Sqrt
{{Sin[x] -> ------------}, {Sin[x] -> ------------}}
2                         2

For the copmplete solution you need to add multiples of 2Pi.

Allan Hayes
De Montfort University, Leicester
hay at haystack.demon.co.uk

```

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