lǎo / shī / yāo / qiú / wǒ / men / xiān / huà / tú / zài / yòng / zhèng / qiē / jì / suàn / zhè / ge / jiǎo / de / dà / xiǎo老师要求我们先画图,再用正切计算这个角的大小。The teacher asked us to draw a diagram first and then use the tangent to calculate the angle.