Prove that: \(\displaystyle\sqrt{{{2}}}{{\sin{{10}}}^{\circ}+}\sqrt{{{3}}}{{\cos{{35}}}^{\circ}=}{{\sin{{55}}}^{\circ}+}{2}{{\cos{{65}}}^{\circ}}\)

alparcero97oy

alparcero97oy

Answered question

2022-03-29

Prove that:
2sin10+3cos35=sin55+2cos65

Answer & Explanation

Regan Gallegos

Regan Gallegos

Beginner2022-03-30Added 9 answers

2sin10+3cos35=2(22sin10+32cos35)
=2(sin45sin10+cos30cos35)
using the product rule for sine and cosine yields
2(sin45sin10+cos30cos35)
=2(cos(4510)cos(45+10)2+cos(30+35)+cos(3530)2)
=cos35cos55+cos65+cos5
=cos(9055)+cos65+(cos5cos55)
=sin55+cos65+2sin(55+52)sin(5552)
=sin55+cos65+212sin(9065)
=sin55+cos65+cos65
=sin55+2cos65

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