The value of the expression 2sin2⁡91∘−12sin2⁡92∘−1…2sin2⁡180∘−1 is equal to

2sin2⁡91∘−12sin2⁡92∘−1…2sin2⁡180∘−1In this product there exists a factor 2sin2⁡135∘−1 which is equal to zeroThus, the product of all terms is zero.