document.write( "Question 1139919: If angle θ is a principal angle that lies in quadrant 3 such that 0° ≤ θ ≤360°, determine the exact values of x, y and r for tan θ = 2/3 \n" ); document.write( "
Algebra.Com's Answer #760443 by Theo(13342)![]() ![]() You can put this solution on YOUR website! tan(theta) = 2/3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "tan(theta) = opposite / adjacent.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "this means that opposite is equal to 2 and adjacent is equal to 3.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "since y is opposite the angle and x is adjacent the angle, then you get y = 2 and x = 3 in the first quadrant.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "r is the hypotenuse of the right triangle formed.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the formula for r is r = sqrt(x^2 + y^2).\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "this makes r = sqrt(3^2 + 2^2) = sqrt(13).\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "in the third quadrant, y = -2 and x = -3.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "tan(theta) = -2 / -3 = 2/3, same as in the first quadrant.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the value of the tangent function is the same whether or not the angle is in the first quadrant or in the third quadrant.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "you can use your calculator to find theta.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "arctan(2/3) = 33.69006753 degrees.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that's in the first quadrant.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that's also called the reference angle.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "in the third quadrant, the equivalent angle would be 180 + 33.69006753 = 213.69006753 degrees.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "the reference angle for 213.69006753 degrees is equal to 213.6906753 degrees minus 180 degrees = 33.6006753.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "use your calculator to find tan(33.69006753) = .666666... = 2/3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "use your calculator to find tan(213.69006753) = .66666.... = 2/3.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "that means that 33.69006753 degrees and 213.69006753 degrees are equivalent angle because they have the same trigonometric values except for the signs.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "sine(33.69006753) = .5547001962 \n" ); document.write( "sine(213.69006753) = -.5547001962\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "same value for sine except for the sign.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "cosine(33.6906753)) = .8320502943 \n" ); document.write( "cosine(213.69006753) = -.8320502943\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "same value for cosine except for the sign.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "we already did the tangent function.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "secant is reciprocal of cosine, so the values will be the same except for the sign.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "cosecant is reciprocal of sine, so the values will be the same except for the sign.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "cotangent is reciprocal of tangent, so the values will be the same.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "here's my picture of the angle in the first quadrant and the third quadrant.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " ![]() \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |