@Test
public void testCos() {

    Assert.assertEquals(1, MathUtil.cos(0), 0);
    Assert.assertEquals(0.5, MathUtil.cos(PI / 3), 0.01);
    Assert.assertEquals(0, MathUtil.cos(HALF_PI), 0.01);
    Assert.assertEquals(1, MathUtil.cos(PI * 2), 0.01);
}