This topic is wrong, it should be a misprint.

According to Sina +cosB=2/3,

Then b = 90, sinA=2/3(A is an acute angle), which is a right triangle.

B is an obtuse angle, for example, b = 9 1, and an acute angle a satisfying the conditions can be found.

B is an acute angle, for example, b = 89, so we can find B that meets the requirements, so C is also an acute angle.

The estimated answer is obtuse triangle.

The title should be Sina +cosA=2/3.

Both sides, sin? A+cos？ A+2 Sinacosa =4/9

∴ 1+2 Sinacosa =4/9

∴2 Sinacosa =-5/9 <; 0

∴ Sina, cosA different number

∴ A is an obtuse angle

Triangle ABC is an obtuse triangle.