题目

阅读下面短文，根据所读内容回答问题。You only have one pair of eyes, so take care of them. When you're in the sun, wear sunglasses. Sunshine can damage your eyes. When your eyes itch or hurt, don't rub them. Your fingers have germs on them. These can get into your eyes and make you sick. Staring at a computer screen can strain your eyes. You blink (眨眼) your eyes 10 times every minute. But when you stare at something, you only blink two or three times per minute. So remember to blink more. This helps your eyes.【1】Why should we take care of our eyes?_____________________已知tanα=3，计算：（1）sinα-cosαcosα+sinα；（2）sinα•cosα的值．