17 - General Trigonometry Questions Answers
(iii) tan69∘+tan66∘+1=tan69∘⋅tan66∘.
Solve
tanx-3cotx=2tan3x(0<x<360)
cosx-sinx=cosy-siny
cos2xcotx+1=cos2x+cotx
tanx - 3/tanx = 2[3tanx-tan3x]/[1-3tan2x]
so [tan2x - 3]/tanx = 2tanx[3-tan2x]/[1-3tan2x]
so [tan2x - 3][1-3tan2x] = 2tan2x[3-tan2x]
so [tan2x - 3][1-3tan2x] + 2tan2x[tan2x-3] = 0
so [tan2x - 3][1-tan2x] = 0
so tanx = 1, -1, √3, -√3
now check the values satisfying last eq.
then put these values in 2nd eq. to get answer.
Find the value :-
(tan69 +tan66) / (1 - tan69.tan66)
use formula of tan(A+B)
Find the max. and min. value of
y = 7cosA + 24sinA
7cosA + 24sinA
= 25[7cosA/25 + 24sinA/25] = 25[cosAcosB + sinAsinB] where tanB = 24/7
= 25cos[A-B] max and min of cos[A-B] = 1 and -1
so max. = 25 and min. = -25
Prove that :-
tanA + 2tan2A + 4tan4A + 8cot8A = cosecA / secA
We have to prove
tanA + 2tan2A + 4tan4A + 8cot8A = cosecA / secA
or tanA + 2tan2A + 4tan4A + 8cot8A = cotA
or 2tan2A + 4tan4A + 8cot8A = cotA - tanA
or tan2A + 2tan4A + 4cot8A = [1-tan2A]/2tanA
or tan2A + 2tan4A + 4cot8A = cot2A
or 2tan4A + 4cot8A = cot2A - tan2A
or tan4A + 2cot8A = [1-tan22A]/2tan2A
or tan4A + 2cot8A = cot4A
or 2cot8A = cot4A-tan4A
or cot8A = [1-tan24A]/2tan4A
it is true so proved
Prove that :-
sin(A+B+C+D) + sin(A+B-C-D) + sin(A+B-C+D) + sin(A+B+C-D) = 4sin(A+B).cosC.cosD
sin(A+B+C+D) = sin(A+B)[cosCcosD-sinCsinD]+cos(A+B)[sinCcosD+cosCsinD]
similarly solve all the terms and add all these terms for getting answer
((1(secA.secA-cosA.cosA))-(1/(cosecA.cosecA-sinA.sinA))).sinA.sinA.cosA.cosA=(1-cosA.cosA.sinA.sinA)/(2+cosA.cosA.sinA.sinA)
Submit the correct question, In first bracket / will be there so
((1/(secA.secA-cosA.cosA))-(1/(cosecA.cosecA-sinA.sinA))).sinA.sinA.cosA.cosA
= [cos2A/sin2A(1+cos2A) - sin2A/cos2A(1+sin2A)]sin2Acos2A
= [cos4A(1+sin2A) - sin4A(1+cos2A)] / [(1+sin2A)(1+cos2A)]
now solve
if x is any real number and cosA=x^2+1/2x then cos A value is
x2+1 > 2x so cosA>1 which is not possible
if x=2Cosθ-Cos2θ and y=2Sinθ-Sin2θ prove that dy/dx=tan(3θ/2)
calculate dx/dθ and dy/dθ
then dy/dx = [2cosθ-2cos2θ]/[-2sinθ+2sin2θ]
now solve
use cosC-cosD = 2sin[(C+D)/2]sin[(D-C)/2]
and sinC+sinD = 2sin[(C+D)/2]cos[(C-D)/2]
What are trigonometrical identities?
sin2A + cos2A = 1 and two similar formulae in terms of tanA, cotA, secA and cosecA
these are identities because these are true for all values of A