Answer:
24/145
Step-by-step explanation:
Trigonometric identities are equalities involving trigonometric functions and remains true for entire values of the variables involved in the equation.
Some trigonometric identities are:
sin(a + b) = sinacosb + cosasinb; sin(a - b) = sinacosb - cosasinb
cos(a + b) = cosacosb - sinasinb; cos(a - b) = cosacosb + sinasinb
Given that sin a = 3/5. sin a = opposite/hypotenuse.
Hence opposite = 3, hypotenuse = 5. using Pythagoras:
hypotenuse² = opposite² + adjacent²
5² = 3² + adjacent²
adjacent² = 16
adjacent = 4
Given that sin a = 3/5. a = sin⁻¹(3/5) = 36.86
cos a = cos 36.86 = 4/5
cos b = -20/29; b = cos⁻¹(-20/29) = 133.6
sinb = sin(133.6) = 21/29
sin(a + b) = sinacosb + cosasinb = (3/5 * -20/29) + (4/5 * 21/29) = -12/29 + 84/145
sin(a + b) = 24/145
