In △abc, a=13, b=14, and c=18. find m∠a.

m∠A = 45.86°

Step-by-step explanation:

A rough sketch of the triangle is shown in the attached pic.

When 3 sides are given and we want to solve for an angle, we use the Cosine Rule. Which is:

Where a, b, p are the lengths of 3 sides (with p being the side opposite of the angle we are solving for) and P is the angel we want to solve for

Thus, we have:

step-by-step explanation:

for exempl this   system of equations   y = x - 3

                                                                y = 2x - 5

look   the line : y = x -3     ( red)

                            the line : y = 2x -5 ( bleus)