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In the triangle ABC, if cos 3 A + cos 3B...

In the triangle ABC, if `cos 3 A + cos 3B+ cos 3C=1`, show that the triangle is obtuse-angled.

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CHHAYA PUBLICATION-MISCELLANEOUS EXAMPLES-TRIGONOMETRY
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  2. If the three side of a triangle be a, b, c and tan theta=(2 sqrt(ab))...

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  3. In the triangle ABC, if cos 3 A + cos 3B+ cos 3C=1, show that the tria...

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  4. Show that : tan 20^(@)+ tan 70^(@)= 2 "cosec" 40^(@)

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  5. Show that : "sin" 2(pi)/(7)+ "sin"(4pi)/(7)-"sin" (6pi)/(7) =4 "sin"...

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  6. Show that : tan 70^(@)=2 tan 40^(@)+ tan 20^(@)+ 4 tan 10^(@)

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  7. The length of hypotenuse and one side of a right -angle triangle are ...

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  8. If "cos" A=(3)/(4), show that 32 "sin" (A)/(2) "sin" (5A)/(2)=11

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  9. If cos A = tan B , cos B= tan C, cos C= tanA, show that sin A= sin B= ...

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  10. If tan (pi cot theta )= cot (pi tan theta), then show that tan theta= ...

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  11. If tan (pi cos theta)= cot (pi sin theta), show that cos (theta-(pi)/(...

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  12. If u(n)=2 cos n theta, then show that u(n+1)= u(1)u(n)-u(n-1), hence, ...

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  13. Show that the value of (cot 3x)/(cot x) cannot lie between (1)/(3) an...

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  14. If (sin theta + cos theta )=sqrt(2) cos theta , show that cot theta =...

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  15. Show that 3(sin x- cos x)^(4)+4 (sin ^(6)x+cos^(6)x)+ 6(sin x+cos x)^(...

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  17. If alpha= (2pi)/(7), then prove that cos alpha+ cos 2 alpha+ cos 4alph...

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  18. In any triangle ABC if sin A sin B sin C+ cos A cos B=1, then show tha...

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  19. If sin theta+ sin phi= sqrt(3)( cos phi- cos theta), then show that si...

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