The teacher will be very surprised to see your correct solution 😉
(tan(2*a) - sin(2*a))*cot(2*a) = 0
a1 = 91.1061867314459
a2 = 37.6991120192083
a3 = 72.256631027719
a4 = 84.8230014093114
a5 = 31.4159267865366
a6 = 53.4070756765307
a7 = 81.6814091761104
a8 = -31.4159267051849
a9 = -53.4070752836338
a10 = -37.6991118771514
a11 = -69.1150386253436
a12 = 94.2477796093525
a13 = 47.123889589354
a14 = -106.814150357553
a15 = -40.8407046898283
a16 = -62.8318532583801
a17 = 75.3982241944528
a18 = 40.840703919946
a19 = 53.4070753627408
a20 = 69.1150385885879
a21 = 9.42477859080277
a22 = -84.8230018263493
a23 = 6.28318528425126
a24 = -3.14159289677385
a25 = 100.530964766599
a26 = -81.6814090380061
a27 = 97.3893725148693
a28 = -6.28318513794069
a29 = 69.1150381602162
a30 = -25.132741473063
a31 = 21.9911485851964
a32 = -12.5663703661411
a33 = -1734.15914475848
a34 = 87.9645943357576
a35 = 65.9734457528975
a36 = -72.2566308741333
a37 = 34.5575190304759
a38 = 28.2743338652012
a39 = -40.8407042660168
a40 = -47.123890151099
a41 = -25.132741632083
a42 = -87.9645943587732
a43 = -18.8495561207399
a44 = -91.106187201329
a45 = -15.7079632965264
a46 = 12.5663704518704
a47 = 97.3893727097471
a48 = -56.5486675191652
a49 = 31.4159271479423
a50 = -34.5575189701076
a51 = -47.1238900492539
a52 = -34.5575189426108
a53 = -94.2477794529919
a54 = -21.9911485864515
a55 = -43.9822971745789
a56 = 15.7079634406648
a57 = -50.2654822953391
a58 = -18.8495556944209
a59 = 59.6902605976901
a60 = -31.4159267959754
a61 = -84.82300141007
a62 = -12.5663700417108
a63 = -3.14159311568248
a64 = -100.530964672522
a65 = 18.8495556796107
a66 = 47.123890018392
a67 = 18.8495554002244
a68 = -62.8318528379059
a69 = 84.8230010166547
a70 = -75.3982238620294
a71 = -65.9734457650176
a72 = 25.1327414478072
a73 = 50.2654824463473
a74 = 56.5486676091327
a75 = 62.8318528326557
a76 = -69.1150386737158
a77 = 3.14159244884412
a78 = -9.42477812668337
a79 = 9.42477821024198
a80 = 62.8318524523063
a81 = 75.3982239388525
a82 = 40.8407042560881
a83 = 78.5398161878405
a84 = 43.982297169427
a85 = -78.5398160958028
a86 = -28.2743337166085
a87 = -91.1061872003049
a88 = 91.1061871583643
a89 = -59.6902604576401
a90 = -97.3893724403711
a91 = 25.1327410188866
a92 = 3.14159287686128
a92 = 3.14159287686128