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If A + B + C =pi, prove that : cos 2A + ...

If `A + B + C =pi`, prove that : `cos 2A + cos 2B + cos 2C = -1-4 cos A cos B cos C `.

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MODERN PUBLICATION-TRIGNOMETRY-EXERCISE
  1. If A + B + C =pi, prove that : cos 2A + cos 2B + cos 2C = -1-4 cos A c...

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  2. Find the radian measure corresponding to the following degree measure ...

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  3. Find the radian measure corresponding to the following degree measure ...

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  4. Find the radian measure corresponding to the following degree measure ...

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  5. Find the radian measures corresponding to the following degree measure...

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  6. Find the radian measure corresponding to the following grade measure :...

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  7. Find the radian measure corresponding to the following grade measure :...

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  8. Find the radian measure corresponding to the following grade measure :...

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  9. Find thedegree measure corresponding to the following measure. (Use pi...

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  10. Find thedegree measure corresponding to the following measure. (Use pi...

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  11. Find thedegree measure corresponding to the following measure. (Use pi...

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  12. Find thedegree measure corresponding to the following measure. (Use pi...

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  13. The angles of a triangle are3x^@, ((4x)/3)^g and (2 pi x)/75 radians. ...

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  14. Express the radians the fourth angle of a quadrilateral which has thre...

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  15. The sum of two angles is 80 grades and their difference is 18^@. Find ...

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  16. The angles of a triangle are in the ratio 1 : 2: 3. Find the angles in...

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  17. The vertical angle of an isosceles triangle is 2/3 rd of each of its b...

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  18. In a right-angled triangle, the difference between two acute angles is...

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  19. The wheel of a carriage is 91 cm in diameter and makes 5 revolutions p...

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  20. A wheel makes 360 revolutions in one minute. Through how many radians ...

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  21. Find the length of the arc of a circle of radius 5 cm subtending an an...

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