text: x=√3 sin 2t+ cos 2t when x=0\nso 0=√3 sin 2t+ cos 2t\ntherefore -cos2t=√3 sin 2t\nso -1=√3 sin 2t/cos 2t\nand -1/√3=tan2t\nso 2t=inverse tan (-1/√3)\n2t=-30, 150, 330, 510, 690...\nt=75, 165, 255, 345.... 90a+75 where a is greater than or equal to 0