Answers

2014-09-18T17:55:13+05:30
Ln a right angled triangle ABC,right angled at B and let angle BCA be α.According to first identity of trigonometry sin²α+cos²α=1
ln the triangle ABC sinα=AB/AC (sinα=opposite side/hypotenuse)
cosα=BC/AC  (cosα=adjacent side/hypotenuse)
Substituting these in the first equation we get
AB²/AC² + BC²/AC² = 1
AB²+BC² = AC²

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actually we prove first identity by using pythagoras theorem,so I need A bit different answer for this.