Question:
One of the angles of the triangle is
One of the angles of the triangle is
Options:
- a) 15°
- b) 30°
- c) 45°
- d) 75°
- a) 15°
- b) 30°
- c) 45°
- d) 75°
correct answer : b)
Explanation:
3x
a
xsin3
= b
xsin
Þ a
b
=
sin
sin
3x
x
Þ 2
=
sin
sin
3x
x
Þ 2 sinx = 3 sinx – 4 sin3x
Þ sinx (1 – 4 sin2x) = 0
Þ sinx
=
1
2
Þ x = 30°
3x
a
xsin3
= b
xsin
Þ a
b
=
sin
sin
3x
x
Þ 2
=
sin
sin
3x
x
Þ 2 sinx = 3 sinx – 4 sin3x
Þ sinx (1 – 4 sin2x) = 0
Þ sinx
=
1
2
Þ x = 30°