2.  𝑆𝑒𝑛2
∝ +𝐶𝑜𝑠2
∝= 1
 𝑆𝑒𝑛2
∝ = 1 − 𝐶𝑜𝑠2
∝
 𝐶𝑜𝑠2
∝= 1 − 𝑆𝑒𝑛2
∝

3.  𝐶𝑜𝑠2 𝑥 𝑑𝑥 =
1+𝐶𝑜𝑠2𝑥 𝑑𝑥
2

1
2
𝑑𝑥 +
1
2
𝐶𝑜𝑠2𝑥𝑑𝑥
 𝑢 = 2𝑥
𝑑𝑢
2
=
2
2

1
2
𝑥 +
1
2
𝐶𝑜𝑠 𝑢
𝑑𝑢
2

1
2
𝑥 +
1
2
.
1
2
𝐶𝑜𝑠 𝑢 𝑑𝑢

1
2
𝑥 +
1
4
𝐶𝑜𝑠 𝑢 𝑑𝑢

1
2
𝑥 +
1
4
𝑆𝑒𝑛 𝑢 + 𝐶

𝒙
𝟐
+
𝑺𝒆𝒏𝟐𝒙
𝟒
+ 𝑪

4.  𝑆𝑒𝑛2𝐴 = 2𝑆𝑒𝑛𝐴𝐶𝑜𝑠𝐴
 𝐶𝑜𝑠2𝐴 = 𝐶𝑜𝑠2 𝐴 − 𝑆𝑒𝑛2 𝐴 = 1 − 2𝑆𝑒𝑛2 𝐴 = 2𝐶𝑜𝑠2 𝐴 − 1
 𝑇𝑎𝑛(2𝐴) =
2𝑡𝑎𝑛𝐴
1−𝑡𝑎𝑛2 𝐴
 𝑆𝑒𝑛 (
𝐴
2
) =
1−𝐶𝑜𝑠 𝐴
2
 𝐶𝑜𝑠 (
𝐴
2
) =
1+𝐶𝑜𝑠 𝐴
2
 𝑇𝑎𝑛 (
𝐴
2
) =
1−𝐶𝑜𝑠 𝐴
1+𝐶𝑜𝑠 𝐴
=
1−𝐶𝑜𝑠 𝐴
𝑆𝑒𝑛 𝐴