SOLUTION: Find the exact value of the expression. Cos 93 cos87-sin93 sin87

Question 1012845: Find the exact value of the expression. Cos 93 cos87-sin93 sin87
Answer by anand429(138) (Show Source): You can put this solution on YOUR website!
Cos 93 cos87-sin93 sin87
=Cos(90+3)*cos(90-3)-sin(90+3)*sin(90-3)
=(cos90*cos3-sin90*sin3)*(cos90*cos3+sin90*sin3) - (sin90*cos3-cos90*sin3)*(sin90*cos3+cos90*sin3)
= ((cos90*cos3)^2-(sin90*sin3)^2) - ((sin90*cos3)^2-(cos90*sin3)^2)
= 0 -(sin3)^2 -(cos3)^2 -0
= -1
RELATED QUESTIONS
find the exact value of the expression cos 255... (answered by lwsshak3)

value of an expression. find the exact value of the expression. cos(sin^-1... (answered by ikleyn)

Find the exact value of... (answered by Nate)

Find the exact value of cos... (answered by Fombitz)

Find the exact value of the expression cos(sin^-1(square root of... (answered by solver91311)

Find the exact value of the expression tan[cos^-1 (1/2)]: (answered by stanbon)

Find the exact value of the expression,... (answered by jsmallt9)

Use a reference angle to find the exact value of the expression? cos... (answered by lwsshak3)

use an appropriate identity to find the exact value of the expression cos... (answered by stanbon,josgarithmetic)