Question #2ec24 Trigonometry Right Triangles Trigonometric Functions of Any Angle 1 Answer P dilip_k Nov 23, 2016 Given #sinA=12/13 and A" is not in 1st quadrant"# So #A# must be in 2nd quadrant Hence #A=sin^-1(12/13)=112.62^@# Again #cosB=3/5 and B" is not in 1st quadrant"# So #B# must be in 4th quadrant Hence #A=cos^-1(3/5)=306.87^@# So #A+B=112.62+306.87=419.49^@# Now #(419.49-360)^@=59.49^@# Hence #A+B-># In the first quadrant. Answer link Related questions How do you find the trigonometric functions of any angle? What is the reference angle? How do you use the ordered pairs on a unit circle to evaluate a trigonometric function of any angle? What is the reference angle for #140^\circ#? How do you find the value of #cot 300^@#? What is the value of #sin -45^@#? How do you find the trigonometric functions of values that are greater than #360^@#? How do you use the reference angles to find #sin210cos330-tan 135#? How do you know if #sin 30 = sin 150#? How do you show that #(costheta)(sectheta) = 1# if #theta=pi/4#? See all questions in Trigonometric Functions of Any Angle Impact of this question 1033 views around the world You can reuse this answer Creative Commons License