What is componendo and dividendo method? Plz explain.

1. cos 20 cos40 cos 60 cos 80=1/16
   

cos20.cos40.cos80=1/8

 Prove that.....Tan 70 = tan 20 + 2 tan 50...

Solve Sinx + Sin3x + Sin5x = 0.

sin 20 sin 40 sin 60 sin 80=3/16

solution of ml agarwal for isc 11std

The chapter trigonometry in RS Aggarwal book (of class 11th) is divided into 6 sub-chapters. But its chapter 5 ( Solution of triangles ) and 6 ( Graphs of trigonometric functions ) are not the topics of NCERT Book.

Now my question is: Should I study these two chapters (5 &6 of RS Aggarwal) as these are not in NCERT Book?

prove the following :

root 3 cosec 20 - sec 20 = 4

prove that tan20 .tan40.tan80=tan60.

sin⁴x+cos⁴x=1-2sin²xcos²x

cos²x + cos²(x + pi/3) + cos²(x - pi/3) = 3/2. prove

cotx cot2x - cot2x cot3x-cot3x cotx=1

sinA . sin(60-A) . sin(60+A) = 1/4 sin3A

if sin alpha + sin beta= a and cos alpha + cos beta= b, show that

1. Sin(alpha+beta)= 2ab/a sq.+b sq.

2. Cos(alpha+beta)= b sq.-a sq./b sq.+a sq.

prove that cos20 cos 40 cos 60 cos 80=1/16.

prove that cos 10.cos30.cos50.cos70 = 3/16

prove that tan 50 = 2 tan 10 + tan40

1.(1+cos pi/ 8) (1+cos 3pi / 8) (1+cos 5pi / 8) (cos 7pi / 8)=1/8

Prove that sin3x + sin 2x – sinx = 4 sinx cos x/2 cos3x/2

sin10*sin50*sin70=1/8?

sin 105 degree +cos 105 degree =cos 45 degree

Prove the following: cosA / 1 - sinA = tan (45 + A/2)

Find the maximum and minimum values of sin^4x + cos^2x and hence or otherwise find the maximum value of sin^1000 x + cox^2008 x

cos4 pi /8+ cos4 3pi /8+ cos4 5pi /8 +cos4 7pi/ 8=3/2  prove it fast rely plssss

PROVE THAT

cos³A + cos³(120+A) + cos³(240+A) = 3/4 cos3A

cos4 pi / 8+cos4 3pi /8 + cos4 5pi / 8 +cos4 7pi /8 =3/2

if A+B=45 degree.show that {1+tanA}{1+tanB}=2

 Prove that:

4 cosA cos(60-A) cos(60+A) = cos3A

in any triangleABC P.T

(b²-c²)cotA + (c²-a²)cotB + (a²-b²)cotC = 0

Prove cos5x=16cos⁵x-20cos³x+5cosx

prove that cos11+sin11/cos11-sin11=tan56

prove using sine rule - 1) sin ( B-C)/2 = b-c/a cos ( A/2)

2)1+cos(A-B) cos C / 1+cos(A-C) cos B = a2+ b2/ a2- c2

3) (b-c)cot (A/2) + (c-a)cot (B/2) + (a-b)cot (C/2) = 0

4) a cos(B-C/2) = (b+c) sin(A/2)

5) c/(a-b) = tan(A/2) + tan(B/2) / tan(A/2) - tan(B/2)

6) a(cos C - cos B) = 2(b-c) cos^2 (A/2)

show that tan3x-tan2x-tanx =tan3x*tan2x*tanx

IF cos(alpha + beta) = 4/5 and sin(alpha - beta) = 5/13

FIND THE VALUE OF tan 2 alpha, where 0 is less than equal to alpha is less than equal to pie/4.

plz reply!!

 Prove that    tan4x= (4tanx(1-tan^2x)) / 1-6tan^x+tan^4x

a tree stands vertically on a hill side which makes an angle of 15degree with the horizontal. from a point on the ground 35m down the hill from the base of the tree, the angle of elevation of the top of the tree is 60degree. find the height of the tree.

ans(35root2m) plese tell the xact solution

Solve the equation:

4sinxcosx + 2sinx + 2cosx + 1 = 0

Show that cos 24 + cos 55 + cos 125 + cos 204 + cos 300= 1/2

prove-

cos²(pi /8) + cos^{2 (}3pi / 8) +cos²(5pi / 8) +cos^{2 (}7pi / 8) = 2

If A+B+C = pai, prove that

sinA + sinB + sinC = 4 cosA/2 cosB/2 cosC/2

find the derivative of cotx by the first principle?

The angles of a triangle are in AP and the ratio of the number of degrees in the least to the number of radians in the greatest is 60:π. Find the angles in degrees and radians.

prove sin²A - sin²B/sinA .cosA- sinB. cosB = tan(A+B)

Prove that : cosA cos2A cos4A cos8A =sin16A / 16sinA

Please explain working

prove that 1+cos2x+cos4x+cos6x= 4cosx cos2x cos3x.

EVALUATE cos(-1125)

Solve sin2x+sin4x+sin6x=0