Question

高一三角函数题一道求解已知角α的终边过点(-3a.2a)(a≠0),求sin^2α+cosα*sinα-1的值

Answer 1

斜边长=√(9a^2+4a^2)=a√13

sina=-3a/a√13=-3√13/13

cosa=2a/a√13=2√13/13

sin^2α+cosα*sinα-1

=9/13+(-3√13/13)(2√13/13)-1

=-3/13-4/13

=-7/13