Notice that there are 3 important angles between π and π/2.They are 30 deg(π/6) , and 60 deg (π/3)45 deg(π/4).The others can be derived by using their location in the quadrant with signs .A litle practice s sufficient .These ratios will appear throughout the college courses in physics and maths and engineering.
Memorising TIP:(Just think why cosines are always negative left of y-axis.Also why sine are negative below the x-axis.)
The easiest ratios are for 45 deg(π/4) ; sin 45=cos 45=1/√2 and tan 45=1
Sin 60=√3 /2 =Cos 30 and Cos 60=1/2 =Sin 30
Print the both image by selecting and give a print command to printer and fill the blanks from memory.
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