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Given: sin a=5/13 in Quadrant 1 and cos b=-12/13 in Quadrant 2; evaluate the following expression. sin(a+b)

1. -120/169
2. -1
3. 0

User Joe Sewell
by
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1 Answer

7 votes

Answer:

The answer to your question is 3. 0

Explanation:

Process

1.- Find the cos a

Opposite side = 5

Hypotenuse = 13

Adjacent side = ?

Adjacent side² = 13² - 5²

= 169 - 25

= 144

Adjacent side = 12

cos a = 12/13

2.- Find the sin b

sin b = 5/13

3.- Use the formula below to find sin(a + b)

sin (a + b) = sina cosb + sin b cos a

- Substitution

sin (a + b) = (5/13)((-12/13) + (5/13)/12/13)

- Simplification

sin (a + b) = -60/169 + 60/13

- Result

sin(a + b) = 0

User Lagarkane
by
5.1k points