+91-87964 74404
FlagBACK
Question icon
Grade 11Trigonometry

Number of solution(s)of the equation sin2A + cos2A = -1/2 ; A belongs in range[0,pi/2]
(a)0
(b)1
(c)2
(d)3
please provide the step-wise solution

Profile image of Arunit Adhikary
7 Years agoGrade 11
Answers icon

1 Answer

Profile image of waqar malik
6 Years ago
squaring on both sides we get..
1+2sin2Acos2A=1/4
(since, 2sinAcosA=sin2A)
therefore, 1+sin4A=1/4
again,            sin4A=-3/4….….….(1)
Since , A ~[0, pi/2]
Therefore, 4A~[0, 2pi]
from equation 1 it is clear that angle 4A will be in 3rd or 4th quadrant,
Hence the equation has only 2 solutions.

Other Related Questions on trigonometry

question mark
In ABC, if cot A+cot B+cot C = cosecA cosecB cosecC, then prove that ABC is right angle triangle.
trigonometry
1 Answer Available

Last Activity: 3 Years ago

question mark
  • Find the general solution of equation tan3∂=cot2∂
For all angles between -720 and +720
trigonometry
1 Answer Available

Last Activity: 4 Years ago

question mark
To prove : Cosec(45 degree - A)Cosec(45 degree + A) = 2SecA
trigonometry
1 Answer Available

Last Activity: 4 Years ago

question mark
Derive a formula for the area of the triangle, given b, A, B, and C. That is, derive the formula: (b^2sinAsinC)/(2sinB)
trigonometry
1 Answer Available

Last Activity: 4 Years ago

question mark
WHAT IS THE LIMIT WHEN X TOWARDS TO 0 OF sin6x/5x ? lim𝑥→0 𝑠𝑖𝑛6𝑥/5𝑥 
trigonometry
1 Answer Available

Last Activity: 4 Years ago