Question

expresse em radianos : a) 130° b) 250°

Answer 1

$\pi$ = 180
x = 130

Multiplica cruzado
180x=130$\pi$
x=130$\pi$/180

Simplificando 
x= 13$\pi$/18

$\pi$ = 180
x = 250
180x=250$\pi$
x=250$\pi$/180       
x=25$\pi$/18

Answer 2

Para passar de graus para radianos pasta multiplicar por $\dfrac{\pi}{180}$. Assim:

$a) 130\cdot\dfrac{\pi}{180} = \dfrac{13\pi}{18} rad$

$b) 250\cdot\dfrac{\pi}{180} = \dfrac{25\pi}{18} rad$