Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Full of errors

Although the authors have very clear ways of explaining mathematical processes and procedures, the book contains plenty of errors, some minor, some major.For example, when explaining the relationships between trig expressions (p. 153), it is stated that sin u = 1/cos u; in fact, a sine is the inverse of a cosecant, not a cosine. A simple but important typographical error.On page 131, it is clearly stated that 9pi/4 radians is a coterminal of 7pi/4 radians; they are at righta angles to each other. The authors arrived at this solution using incorrect math, which does not lead me to believe that they are checking their work very well.I have found many more such errors, and I am disappointed with the book. I didn't buy it from Amazon, and I'm taking it back to the store for a refund.