(cos85°+sin25°cos30°)/cos25°=
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(cos85°+sin25°cos30°)/cos25°

= {cos(60°+ 25°) + sin25°cos30°} /cos25°

= {cos60°cos25° - sin60°sin25° + sin25°cos30°} /cos25°

= {cos60°cos25° - sin25°(sin60° - cos30°) } /cos25°

= cos60°cos25° / cos25°

= cos60°

= 1/2

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