I measure the angle using a protractor.

One angle of this triangle is 90 degrees.

I will work using this laptop.

He used a stick to measure the depth of the river.

He measured the size of the room.

The mountain rises at a steep angle.

He is using that coat from winter to spring.

You need to use your head to solve this problem.

The astronomer conducted an observation of the night sky.

He likes to observe celestial bodies.