Advertisements
Advertisements
Question
Find the value of:
sin 15°
Solution
sin 15°
= sin (45° – 30°)
= sin 45° cos 30° – cos 45° sin 30°
= `(1/sqrt(2))(sqrt(3)/2) - (1/sqrt(2))(1/2)`
= `(sqrt(3) - 1)/(2sqrt(2)`
Notes
Answer given in the textbook is `(sqrt(3) + 1)/(2sqrt(2)`. However, as per our calculation it is `(sqrt(3) - 1)/(2sqrt(2)`.
APPEARS IN
RELATED QUESTIONS
Find the values of:
cos 75°
Find the value of :
tan (– 690°)
Find the value of :
sec 240°
Find the value of :
sec (– 855°)
Find the value of :
cot (– 1110°)
Prove the following:
`(cos(pi + x) cos(-x))/(sin(pi - x)cos(pi/2 + x))` = cot2x
Prove the following:
`cos((3pi)/2 + x) cos(2pi + x)[cot((3pi)/2 - x) + cot(2pi + x)]` = 1
Prove the following:
sec 840° . cot (– 945°) + sin 600° tan (– 690°) = `3/2`
Select the correct option from the given alternatives :
If sin θ = n sin (θ + 2α), then tan (θ + α) is equal to
Select the correct option from the given alternatives :
Let 0 < A, B < `pi/2` satisfying the equation 3 sin2A + 2 sin2B = 1 and 3 sin 2A − 2 sin 2B = 0 then A + 2B is equal to ______
Prove the following:
sin 20° sin 40° sin 80° = `sqrt(3)/8`
Prove the following:
cos 36° = `(sqrt(5) + 1)/4`
Prove the following:
sin 36° = `(sqrt(10 - 2sqrt(5)))/4`
Prove the following:
tan6° tan42° tan66° tan78° = 1
Prove the following:
sin47° + sin61° − sin11° − sin25° = cos7°
If θ = `(17π)/3` then, tan θ – cot θ = ______.
`(1 - 2[cos 60^circ - cos 80^circ])/(2 sin 10^circ)` = ______.
The value of sin 495° is ______.
The value of sin(– 1125°) is ______.
The value of `cos((41π)/4)` is ______.
The value of `cos π/8 + cos (3π)/8 + cos (5π)/8 + cos (7π)/8` is ______.
The value of `2 cot^2(π/6) + 4 tan^2(π/6) - 3 "cosec"(π/6)` is ______.
The value of cos 480° sin 150° + sin 600° cos 390° is ______.
The value of `cos^2 π/16 + cos^2 (3π)/16 + cos^2 (5π)/16 + cos^2 (7π)/16` is ______.
In a ΔABC, if ∠A = `π/2`, then cos2 B + cos2 C is equal to ______.
If `sin A - sqrt(6) cos A = sqrt(7) cos A`, then `cos A + sqrt(6) sin A` is equal to ______.
If sin A + sin B + sin C = 3, then cos A + cos B + cos C is equal to ______.
In a ΔPQR, if 3 sin P + 4 cos Q = 6 and 4 sin Q + 3 cos P = 1, then ∠R is equal to ______.
The value of cos (270° + θ) cos (90° – θ) – sin (270° – θ) cos θ is ______.
The value of sin 135° cosec 225° tan 150° cot 315° is ______.
cos 1°. cos 2°. cos 3° ...... cos 179° = ______.
