4. Integration By Part
• 𝑥 𝑠𝑒𝑐2 𝑥 𝑑𝑥 = 𝑢𝑣 − 𝑣 𝑑𝑣 = 𝑥 𝑡𝑎𝑛 − tan 𝑥 𝑑𝑥
• 𝑢 = 𝑥 𝑑𝑣 = 𝑠𝑒𝑐2 𝑥 𝑑𝑥
• 𝑑𝑢 = 𝑑𝑥 𝑣 = tan 𝑥
• tan 𝑥 𝑑𝑥 =
sin 𝑥
cos 𝑥
𝑑𝑥 = − ln cos 𝑥
5. Trigonometric Integral
• A)
• Case 1: 𝑠𝑖𝑛5 𝑥= sin 𝑥 (1−𝑐𝑜𝑠2 𝑥)
2
• Case 2: 𝑐𝑜𝑠5
𝑥= cos 𝑥 (1−𝑠𝑖𝑛2
𝑥)
2
• Case 3: 1. 𝑠𝑖𝑛22𝑎𝑥 = 1 −
cos 2𝑎𝑥
2
2. 𝑐𝑜𝑠2
2𝑎𝑥 = 1 +
cos 2𝑎𝑥
2• B)
• Case 1: 𝑠𝑒𝑐4
𝑥= (𝑡𝑎𝑛2
𝑥 + 1) 𝑠𝑒𝑐2
𝑥
• Case 2: 𝑠𝑒𝑐3 𝑥 𝑡𝑎𝑛3 𝑥 = 𝑠𝑒𝑐2 𝑥 (𝑠𝑒𝑐2 𝑥 - 1) 𝑠𝑒𝑐 𝑥 𝑡𝑎𝑛 𝑥
• Case 3: 𝑠𝑒𝑐3 𝑥 = 𝑠𝑒𝑐 𝑥 𝑠𝑒𝑐2 𝑥 = 𝑠𝑒𝑐 𝑥 (𝑠𝑒𝑐2 𝑥+1)
• Case 4: 𝑠𝑒𝑐 𝑥 𝑡𝑎𝑛2
𝑥= 𝑠𝑒𝑐 𝑥 (𝑠𝑒𝑐2
𝑥 - 1)
6. Trigonometric Integral
• C)
• 1 ± cos 2𝑎𝑥 = 2 𝑐𝑜𝑠2 𝑎𝑥 = 1 + cos 2 ax
= 2 𝑠𝑖𝑛2 𝑎𝑥 = 1 – cos 2 ax
• D)
• Case 1: {sin ax sin bx => sin ax sin bx = ½ [cos(a-b) x – cos (a +b)x]
• Case 2: {sin ax cos bx => sin ax cos bx = ½ [sin(a-b) x – sin (a +b)x]
• Case 3: {cos ax cos bx => cos ax cos bx = ½ [cos(a-b) x + cos (a +b)x]