Si sen =−7/25 y cos= −4/5, determine:
sen (α+β)=
Answers
Answer:
sin(α+β)= 12/25
Step-by-step explanation:
sinα= -7/25
cosβ= -4/5
sin(α+β)= sinα cosβ + cosα sinβ
by Pythagoras theorem
adj= √(hypo)^2-(opp)^2
sinα=-7/25
cosα= 24/25
by Pythagoras theorem
adj= √(hypo)^2-(opp)^2
cosβ= -4/5
sinβ= 3/5
sin(α+β)= sinα cosβ + cosα sinβ
= (-7/25 ) (-4/5) + (24/25) (3/5)
= -27/25+ 39/25
= 12/25
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Given :- sin A = (-7/25) , cos B = (-4/5) ,
To Find :-
- sin (A + B) = ?
Answer :-
→ sin A = (-7/25) = P/H
so, using pythagoras theorem,
→ B = √(H² - P²) = √(625 - 49) = √576 = 24
then,
→ cos A = B/H = (-24/25)
similarly,
→ cos B = (-4/5) = B/H
so,
→ P = √(5² - 4²) = 3
then,
→ sin B = P/H = (-3/5)
now,
→ sin(A + B) = sinA * cosB + cosA * sinB
→ sin(A + B) = (-7/25) * (-4/5) + (-24/25) * (-3/5)
→ sin(A + B) = (28/125) + (72/125)
→ sin(A + B) = (100/125)
→ sin(A + B) = (4/5) (Ans.)
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