Question

4. Find o such that 2 cos 0. sin 0 - cos 0 = 0 if 0°< 0 < 90°.​

Answer 1

Answer:

Step-by-step explanation:

0<θ<90

∘

secθ=cosec60

⇒secθ=

sin60

1

​

=

3

​

2

​

⇒

cosθ

1

​

=

3

​

2

​

⇒cosθ=

2

3

​

​

⇒θ=30

∘

2cos

2

θ−1=2(cos30)

2

−1

⇒2×(

2

3

​

​

)

2

−1

⇒2×

4

3

​

−1⇒

2

3

​

−1=

2

1

​

∴2cos

2

θ−1=

2

1

​

Answer 2

Step-by-step explanation:

The first person to document zero as a number in its own right was the astronomer and mathematician Brahmagupta in 628 CE.