Find the radian measure corresponding to the following degree measures:

(vii) 125^o 30’ (viii) -47^o 30′

Solution:

We know that

180° = π rad

In terms of radians, 1° = π/ 180 rad

(vii) 125° 30′

We know that,

30′ = (1/2) °

125° 30’ = (125 1/2) ° = (251/2) ^o

125° 30’ = (251/2 × π/180) rad

125° 30’ = 251π/360

Therefore, the radian measure of 125° 30′ is 251π/360

(viii) -47° 30′

We know that,

30′ = (1/2) °

-47° 30’ = – (47 1/2) °

-47° 30’ = – (95/2) ^o

-47° 30’ = – (95/2 × π/180) rad

-47° 30’ = – 19π/72

therefore, the radian measure of -47° 30′ is – 19π/72