The teacher will be very surprised to see your correct solution 😉
___ /x\ \/ 3 cos|-| = ----- \2/ 2
pi
x1 = --
3
11*pi
x2 = -----
3
x2 = 11*pi/3
sum
pi 11*pi -- + ----- 3 3
=
4*pi
product
pi 11*pi --*----- 3 3
=
2 11*pi ------ 9
11*pi^2/9
x1 = 1.0471975511966
x2 = 13.6135681655558
x3 = -86.9173967493176
x4 = 99.4837673636768
x5 = 86.9173967493176
x6 = -99.4837673636768
x7 = 36.6519142918809
x8 = -13.6135681655558
x9 = 51.3126800086333
x10 = -36.6519142918809
x11 = -76.4454212373516
x12 = -89.0117918517108
x13 = 49.2182849062401
x14 = -49.2182849062401
x15 = 38.7463093942741
x16 = 63.8790506229925
x17 = -11.5191730631626
x18 = 26.1799387799149
x19 = -164.410015537866
x20 = -225.147473507269
x21 = 74.3510261349584
x22 = -24.0855436775217
x23 = -2286.03225426217
x24 = -12881.5770772693
x25 = -61.7846555205993
x26 = 24.0855436775217
x27 = 61.7846555205993
x28 = 11.5191730631626
x29 = -74.3510261349584
x30 = -63.8790506229925
x31 = -26.1799387799149
x32 = 89.0117918517108
x33 = -1.0471975511966
x34 = 76.4454212373516
x35 = 137.182879206754
x36 = -38.7463093942741
x37 = -51.3126800086333
x37 = -51.3126800086333