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Mathematics
Mathematics
Problem
Evaluate
E
=
(
sin
70
∘
cos
25
∘
−
cos
70
∘
sin
25
∘
)
+
(
cos
70
∘
cos
25
∘
+
sin
70
∘
sin
25
∘
)
\displaystyle E=\bigl(\sin70^{\circ}\cos25^{\circ}-\cos70^{\circ}\sin25^{\circ}\bigr)+\bigl(\cos70^{\circ}\cos25^{\circ}+\sin70^{\circ}\sin25^{\circ}\bigr)
E
=
(
sin
7
0
∘
cos
2
5
∘
−
cos
7
0
∘
sin
2
5
∘
)
+
(
cos
7
0
∘
cos
2
5
∘
+
sin
7
0
∘
sin
2
5
∘
)
. a)
3
\sqrt3
3
b)
2
\sqrt2
2
c) 1 d)
2
2
\dfrac{\sqrt2}{2}
2
2
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