I hope that helps, coz l've done what i know
The unit circle is a circle with radius

, so you have

where

is measured in radians, so

.
9.9
With right triangles you can use the equation a^2 + b^2 = c^2. Since both a and b are 7, that makes it 7^2 + 7^2 = c^2 and from there 49 + 49 = c^2 and then 98 = c^2. Then go find C, you find the square root of 98 which is 9.899494937 or rounded as 9.9
Keep in mind a^2 + b^2 = c^2 only works for right triangles, it won’t work for any other ones.