Can do it by using a combination of either the 'Wave' effect or using a stripe pattern and filling the background for creating the lines and then, the 'Polar Distortion' effect set to 'Rectangular to Polar' to distort the lines into the star-burst.
Alternatively you use the pen tool, create one of the triangles and then do a copy+paste+rotate around a centre point - same for illustrator i would imagine.
There's plenty of tutorials, especially on Youtube, for this effect!