Class 9 MAHARASHTRA STATE TEXTBOOK BUREAU Solutions Maths Chapter 8 - Trigonometry
Trigonometry Exercise Ex. 8.1
Solution 1
Solution 2
Solution 3
Solution 4
(i).sin α, cos α, tan α
(ii) sin θ, cos θ, tan θ
Trigonometry Exercise Ex. 8.2
Solution 1
Solution 2(i)
5 sin30° + 3 tan 45°
Solution 2(ii)
Solution 2(iii)
2 sin 30° + cos 0° + 3 sin 90°
=
= 1 + 1 + 3
= 5
Solution 2(iv)
Solution 2(v)
cos2 45° + sin2 30°
Solution 2(vi)
cos 60° × cos 30° + sin 60° × sin 30°
Solution 3
Solution 4
Sin2 θ + cos2 θ = 1
sin2 θ
+ 
=
1
sin2 θ
+ 
=
1
sin2 θ
+ = 1 -
sin2 θ
+ = 
sin2θ
= 
Thus, the value
of sin2θ is
Trigonometry Exercise Problem set 8
Solution 1(i)
We know that, sin θ = cos(90 - θ).
Also,
cos θ = sin (90 - θ)
and tan θ = cot (90 - θ)
Thus option A is correct.x`
Solution 1(ii)
We know that,
sin 90° = 1
Thus, option D is correct.
Solution 1(iii)
2 tan 45° + cos 45° - sin 45°
= 2
Thus, option C is correct.
Solution 1(iv)
= 1
Solution 2
In right ∆TSU
TU2 = SU2 + TS2
TU2 = 122 + 52 = 144 + 25 = 169
TU = 13
Now,
Also,
Solution 3
In right ∆YXZ
YZ2 = XZ2 + XZ2
XY2 = YZ2 - XZ2
XY2 = 172 - 82 = 289 - 64 = 225
XY = 15
Now,
Also,
Solution 4
Solution 5
(i)
Sin 20° = cos (90° - 20°) = cos 70°
(ii)
Tan 30° =
Tan 60° =
Now,
Thus,
Tan 30° x tan 60° = 1
(iii)
Cos 40° = sin (90° - 40°) = sin 50°
