Sin(90-a)+cos(180-a)+tg(270+a)

Предыдущий
вопрос Следующий
вопрос

sin90 = 1
cos180 = -1
tg270 = undefined

So the expression simplifies to:

1 + (-1) + undefined

1 + (-1) is equal to 0, and since tg(270+a) is undefined, the final answer is also undefined.