Answer:
1. sin and cos 2. complementary 3. sinA = cosB 4. 80° 5. 17
Step-by-step explanation:
1. cofunctions: having the same value at complementary angles
sin θ = cos (90 - θ), or cos θ = sin(90 - θ)
2. complementary: two angles sum to 90°, supplementary: two angles sum to 180°
one of the angle in a right triangle must be a right angle = 90°
180°(sum of angles of a triangle) - 90° = 90°(the sum of the other two angles) => which is complementary
3. sinA = cosB
4. cos θ = sin(90 - θ)
=> cos 10° = sin(90 - 10°)
=> cos 10° = sin(80°)
5. sin θ = cos (90 - θ)
=> sin 73° = cos (90 - 73°)
=> sin 73° = cos (17°)
