Use Sum and Difference Formulas for Cosines and Sines
-$\sin 25 ^ { \circ } \cos 35 ^ { \circ } + \cos 25 ^ { \circ } \sin 35 ^ { \circ }$
A) $\frac { \sqrt { 3 } } { 2 }$
B) $\frac { 1 } { 2 }$
C) $\frac { 5 } { 12 }$
D) $\frac { \sqrt { 3 } } { 3 }$

Question

Quizplus · Accepted Answer

Using the sum formula for sines, we have:$\sin 25 ^ { \circ } \cos 35 ^ { \circ } + \cos 25 ^ { \circ } \sin 35 ^ { \circ } = \sin (25 ^ { \circ } + 35 ^ { \circ }) = \sin 60 ^ { \circ } = \frac { \sqrt { 3 } } { 2 }$

Use Sum and Difference Formulas for Cosines and Sines - sin⁡25∘cos⁡35∘+cos⁡25∘sin⁡35∘\sin 25 ^ { \circ } \cos 35 ^ { \circ } + \cos 25 ^ { \circ } \sin 35 ^ { \circ }sin25∘cos35∘+cos25∘sin35∘

Use Sum and Difference Formulas for Cosines and Sines
- $\sin 25 ^ { \circ } \cos 35 ^ { \circ } + \cos 25 ^ { \circ } \sin 35 ^ { \circ }$