How to calculate this? sin^2(110^@)+sin^2(200^@).

1 Answer
Nghi N
Apr 25, 2017

1

Explanation:

Use trig identity and properties of complementary and supplementary arcs:
cos^2 a + sin^2 a = 1
In this case:
sin (110) = sin (90 + 20) = cos (20)
sin^2 (110) = cos^2 (20)
sin (200) = sin (180 + 20) = - sin (20)
sin^2 (200) = sin^2 (20)
Finally:
sin^2 (110) + sin^2 (200) = cos^2 (20) + sin^2 (20) = 1

Related questions
Impact of this question
4884 views around the world
You can reuse this answer
Creative Commons License