Starting from the x axis, we must rotate 35° counterclockwise to reach the n axis.

With the stress transformation equations, the sign convention for θ is as follows:

• θ is positive if we must rotate from the x axis to the n axis in a counterclockwise direction.
• θ is negative if we rotate in a clockwise direction to get from the x axis to the n axis.

Therefore, to compute the state of stress on plane AB we use a value of:

in the stress transformation equations.