Find the resultant of two vectors of 3 units and 4 units acting at a point o at an angle of 45° with each other. Please use triangular method.

I have no idea what the triangular method is.

If Ax = 3 and Ay = 0
and
Bx = 4 cos 45 and By = 4 sin 45
then Rx= 3 + 4*0.707 = 5.83
and Ry = 4*0.707 = 2.83
| R | = sqrt (5.83^2 + 2.83^2)
tan angle between = 2.83/5.83

Could be the result of using the cosine law on the triangle created after

sketching the situation.
r^2 = 3^2 + 4^2 - 2(3)(4)cos135°
= 25 - 24(-√2/2) = ...
r = appr 6.48 units