Question

The measure of angel a is one half the measure of angle c. The measure of angle B is 90 find the measure of angel a

Answer 1

Note: This is the answer if you are talking about a triangle because you didn't specify that.

A=30°

I'm going to assume this is a triangle so if I'm wrong tell me in the comments. If it is a triangle all the angles should add up to 180 degrees. We already know that one is 90 so the other two angles have to add up to 90 (since 90+90=180). C is twice as much as A. So 1/3 of 90 is A and 2/3 of 90 is C. A would be 30°. In summary A=30° B=90° C=60°. Hopefully I understood your question correctly and this helped you. Also sorry it took a while to answer.