Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

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bob bundy
2013-05-26 23:54:59

Won't squaring introduce extraneous solutions?

#### In post 4 I wrote:

Squaring will give the solutions.  It may also generate values that don't fit the original because (-z)^2 = z^2

But, in this example, as we only want 0 < x < 180, the single, correct solution may be found by squaring.

Bob

anonimnystefy
2013-05-26 23:31:22

Won't squaring introduce extraneous solutions?

zetafunc.
2013-05-26 22:23:27

Letting x = arccos(u) or arcsin(u) is another way, although the method is mostly the same as in posts #2 and #3.

bob bundy
2013-05-26 22:18:10

hi atuturay

Welcome to the forum.

Squaring will give the solutions.  It may also generate values that don't fit the original because (-z)^2 = z^2

An alternative starts like this:

Solve this firstly for x plus alpha and hence get x.

Bob

{7/3}
2013-05-26 21:40:11

Bring cos x to left side and squre.

zetafunc.
2013-05-26 21:16:20

Squaring both sides might help.

atuturay
2013-05-26 20:53:09

Hiii,

I don't know how to work out the root of the equation sinx= 1+cosx for 0°<x<180°