He warned about the dangers of nuclear warheads.

Finding the Summer Triangle is helpful for remembering constellations.

The Winter Triangle is shining in the night sky.

A straight angle is 180 degrees.

He decided the course while looking at the sea chart.

The sum of the internal angles of this triangle is 180 degrees.

The internal angle of this figure is 90 degrees.

Daily exercise is indispensable in my life.

The buyer for this house has not been found yet.

My father underwent surgery for hemorrhoids.