Question

Using trigonometric tables, find the approximate value of cosec 48° 34'.

Answer 1

Given: Find cosec 48° 34'.

Step-wise calculation:

1. cosec θ = `1 /sin θ`.

So, we need sin 48° 34'.

2. Use trigonometrical tables interpolate between 48° and 49°:

sin 48° = 0.7431448

sin 49° = 0.7547096

Difference for 1° = 0.7547096 – 0.7431448

= 0.0115648

Difference per 1' = `0.0115648/60`

= 0.0001927467

For 34' the increment = 34 × 0.0001927467

= 0.0065533

sin 48°34' ≈ 0.7431448 + 0.0065533

= 0.7496981

3. cosec 48° 34' = `1/0.7496981`

cosec 48° 34' ≈ 1.333726

cosec 48° 34'  ≈ 1.3337