In triangle ABC, /C = (2pi)/3 then the v...

In triangle `ABC, /_C = (2pi)/3` then the value of `cos^2 A + cos^2 B - cos A.cos B` is equal

A

`(3)/(4)`

B

`(3)/(2)`

C

`(1)/(2)`

D

`(1)/(4)`

Text Solution

Verified by Experts

The correct Answer is:

A

Topper's Solved these Questions

COMPOUND ANGLES
VK JAISWAL|Exercise Exercise-2 : One or More than One Answer is/are Correct|26 Videos
COMPOUND ANGLES
VK JAISWAL|Exercise Exercise-3 : Comprehension Type Problems|12 Videos
COMPLEX NUMBERS
VK JAISWAL|Exercise EXERCISE-5 : SUBJECTIVE TYPE PROBLEMS|8 Videos
CONTINUITY, DIFFERENTIABILITY AND DIFFERENTIATION
VK JAISWAL|Exercise EXERCISE (SUBJECTIVE TYPE PROBLEMS)|23 Videos

Similar Questions

Explore conceptually related problems

In triangle ABC,/_C=(2 pi)/(3) then the value of cos^(2)A+cos^(2)B-cos A*cos B is equal

If a, b, c are the sides of a triangle ABC and |(1,a,b),(1,c,a),(1,b,c)|=0, then the value of cos^2 A + cos^2 B +cos^2 C is equal to

If A,B,C are the angles of triangle ABC, then the minimum value of |{:(-2,cos C , cos B),(cos C , -1, cos A ) , (cos B , cos A , -1):}| is equal to :

If a, b, c are sides of the triangle ABC and |(1,a, b),(1,c,a),(1,b,c)|=0 , then the value of cos 2A+cos 2B+cos 2C is equal to

The chord AB of a circle subtends an angle of frac {2pi}{3} at a point C on the circumference. Prove that the value of cos^(2)A + cos^(2)B - cos A*cos B is invariant for all such triangles ABC.

In a Delta ABC, the value of (a cos A+b cos B+c cos C)/(a+b+c) is equal to

ABC is a right angled triangle with angleA=90^(@) .Then the value of cos^(2)A+cos^(2)B+cos^(2)C is :

In a Delta ABC,a=5,b=3 and c=7, then the value of 3cos C+7cos B is equal to

In triangle ABC,cos A+2cos B+cos C=2, then-

VK JAISWAL-COMPOUND ANGLES-Exercise-5 : Subjective Type Problems

In triangle ABC, /C = (2pi)/3 then the value of cos^2 A + cos^2 B - co...
Text Solution
|
Let P=(sin80^(@)sin65^(@) sin35^(@))/(sin20^(@)+sin50^(@)+sin110^(@))...
Text Solution
|
The value of expression (1-cot23^(@))(1-cot22^(@)) is equal to :
Text Solution
|
If tanA and tanB the roots of the quadratic equation, 4x^(2)-7x+1=0 th...
Text Solution
|
A(1)A(2)A(3)………A(18) is a regular 18 sided polygon. B is an external p...
Text Solution
|
If 10sin^(4)alpha+15cos^(4)alpha=6 and the value of 9"cosec"^(4)alpha...
Text Solution
|
The value of (1+tan\ (3pi)/8*tan\ pi/8)+(1+tan\ (5pi)/8*tan\ (3pi)/8)+...
Text Solution
|
If alpha=pi/7 then find the value of (1/cosalpha+(2cosalpha)/(cos2alph...
Text Solution
|
Given the for a,b,c,d in R, if a sec(200^@)- ctan(200^@)=d and b sec(...
Text Solution
|
The expression 2"cos"(pi)/(17)*"cos"(9pi)/(17)+"cos"(7pi)/(17)+"cos"(9...
Text Solution
|
If the expression (sin theta sin2theta+sin3theta sin60theta+sin4theta...
Text Solution
|
Let a=sin10^(@), b =sin50^(@), c=sin70^(@)," then " 8abc((a+b)/(c ))((...
Text Solution
|
If sin^(3)theta+sin^(3)(theta+(2pi)/(3))+sin^(3)(theta+(4pi)/(3))=a s...
Text Solution
|
If sum(r=1)^(n)((tan 2^(r-1))/(cos2^(r )))=tanp^(n)-tan q, then find t...
Text Solution
|
If x=sec theta-tan theta and y=cosectheta+cot theta,then Find y-x-xy...
Text Solution
|
If cos18^(@)-sin18^(@)=sqrt(x)sin27^(@), then x=
Text Solution
|
The value of 3(sin1-cos1)^(4)+6(sin1+cos1)^(2)+4(sin^(6)1+cos^(6)1) i...
Text Solution
|
Q. x=a satisfy the equation 3^(sin 2x+2 cos^2 x)+3^(1-sin 2x+2 sin^ 2x...
Text Solution
|
The minimum value of (sintheta+c o s e ctheta)^2+(costheta+sectheta)^...
Text Solution
|
If tan20^(@)+tan40^(@)+tan80^(@)-tan60^(@)=lambda sin40^(@), then lamb...
Text Solution
|
If K^(@) lies between 360^(@) and 540^(@) and K^(@) satisfies the equa...
Text Solution
|