.
A.
B.
C.
D.
Step 1: sin θ =
1213, 0° < θ < 90°

Step 2: cos θ =
513Step 3: 0° <
θ2 < 45°, therefore,
θ2 is a first-quadrant angle.
Step 4: sin
θ2 = +
1 - cos θ2[Use half - angle formula.]
Step 5: =
1- 5 132[Substitute the values.]
Step 6: =
826Step 7: =
21313