What is the number of degrees in the acute angle formed by the hands of a clock at 6:50?

In this exercise, we find a formula for the angle formed by two lines in a coordinate plane. 

(a) If is a line in the plane and is the angle formed by the line and the -axis as shown in the figure, show that the slope of the line is given by 

(b) Let and be two nonparallel lines in the plane with slopes and , respectively. Let be the acute angle formed by the two lines (see the following figure). Show that 

(c) Find the acute angle formed by the two lines

and  

(d) Show that if two lines are perpendicular, then the slope of one is the negative reciprocal of the slope of the other. [Hint: First find an expression for .]

How to find the measure of each acute angle in a right angle if one of the acute angle is twice the difference of acute angle and 12.

a) calculate the number of degrees for a measure of   sketch this angle in standard position.

b) calculate the number of radians for a meaure of -210degrees. sketch this angle in standard position.