Lines
ab
and
ac
tangent to circle k(o) at b and c respectively. find bc, if m∠oab=30°, and ab=5 cm.

5 cm

Step-by-step explanation:

If AB is tangent to the circle k(O), then radius OB is perpendicular to segment AB.

If BC is tangent to the circle k(O), then radius OC is perpendicular to segment AC.

Consider two right triangles ABO and ACO. In these triangles:

By HL theorem, triangles ABO and ACO are congruent. Then

Hence, ∠BAC=∠OAB+∠OAC=30°+30°=60°.

Consider triangle ABC, this triangle is isosceles triangle. In isosceles triangles angles adjacent to the base are congruent, thus

∠CBA=∠BCA=1/2(180°-60°)=60°.

Therefore, triangle ABC is an equilateral triangle, so BC=AB=AC=5 cm.

option (b) is correct

step-by-step explanation:

to find the solution of this system, we need to convert it into reduced row-echelon form. we have,

after applying row operations r2 -> r2/2 and r3 -> r3/3, we get,