sin12osin48osin54o is equal to
116
132
18
14
Explanation for the correct answer:
Simplifying the given expression:
⇒sin12°sin48°sin54°⇒12(2sin12°sin48°)sin54°
Using the formula 2sinxsiny=cos(x–y)–cos(x+y)
⇒12cos(12°–48°)–cos(12°+48°)sin54°⇒12cos36°–cos60°sin54°⇒12cos36°sin54°–12sin54°⇒142cos36°sin54°–sin54°]
Using the formula 2cosxsiny=sin(x+y)–sin(x–y)
⇒14sin(36°+54°)–sin(36°–54°)–sin54°⇒14sin90°+sin18°–sin54°⇒141+5–14–5+14⇒144+5-1-5-14⇒144-24⇒1424⇒18
Hence, option C is correct.
Find answers to the following. Write and indicate how you solved them.(i) Is 59 equal to45?(ii) Is 916 equal to 59?(iii) Is 45 equal to 1620?(iv) Is 115 equal to 430?
Evaluate :cos48°-sin42°