Given: circle o; intercepts ; d intercepts prove: two statements are missing reasons. what reason can be used to justify both statements 2 and 3? statements reasons 1. circle o; 1. given 2. 2. ? 3. 3. ? 4. 4. substitution property 5. 5. definition of congruent angles inscribed angles theorem third corollary to the inscribed angles theorem central angle of a triangle has the same measure as its intercepted arc. formed by a tangent and a chord is half the measure of the intercepted arc.