Final answer:
a) Find sinθtanθ, given cosθ=2/3 b) Simplify sin(180∘ −θ)+cosθ⋅tan(180∘ + θ). c) Solve cos^2 x−
Step-by-step explanation:
Let's simplify the expression step by step:
1. Start with the trigonometric identities for sine and cosine of complementary angles:
- s in(90 - θ) = cos(θ)
- cos(90 - θ) = sin(θ)
2. Substitute these identities into the expression:
- sin^2(90 - θ) + cos^2(90 - θ) = [cos(θ)]^2 + [sin(θ)]^2
3. Now, remember the Pythagorean trigonometric identity:
- sin^2(θ) + cos^2(θ) = 1
4. Apply the Pythagorean identity to the expression:
- [cos(θ)]^2 + [sin(θ)]^2 = 1
So, sin^2(90 - θ) + cos^2(90 - θ) is equal to 1.