dorcus Posted January 26, 2006 Share Posted January 26, 2006 can someone help me solve these two equations (and please explain)? log9 (q) = log12 (p) = log18 (q + p) what is q and what is p? and.... sinA + sinB = (square root 2) over 2 cosA + cosB = (square root 6) over 2 sin(A + B) = ? Thanks in advanced! Link to comment Share on other sites More sharing options...

Tartaglia Posted January 26, 2006 Share Posted January 26, 2006 Sin A + Sin B = 2 Sin((A+B)/2) * Cos((A-B)/2) = sqrt(2)/2 (1) CosA + CosB = 2Cos((A+B)/2)*Cos((A-B)/2) = sqrt(6)/2 (2) (1)/(2) gives tan((A+B)/2) = 1/sqrt(3) therefore (A+B)/2 = pi/6 therefore A+B = pi/3 Sin(A+B) = sqrt(3)/2 Link to comment Share on other sites More sharing options...

EvoN1020v Posted January 27, 2006 Share Posted January 27, 2006 Are you talking about multiple angle identities? [math]sin(A+B) = sinAcosB + sinBcosA[/math] Also, the question about what is "p and q". They are just a variable for the value of the answer when you put it in the orginal exponent form. i.e. [math]log_{2}p = 3[/math] intends [math]2^{3}=p[/math] and the value of "p" is 8. Link to comment Share on other sites More sharing options...

Tartaglia Posted January 27, 2006 Share Posted January 27, 2006 p= 24.8638977 q=17.13963918 Link to comment Share on other sites More sharing options...

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