Answer:
The angle is
![\theta = 15.48^o](https://img.qammunity.org/2021/formulas/physics/college/kz2dzm6hjwpw3u2vub80i6r1038cspbgtc.png)
Step-by-step explanation:
From the question we are told that
The distance of the dartboard from the dart is
![d = 3.66 \ m](https://img.qammunity.org/2021/formulas/physics/college/316txgvqc9oegcqiogpw19dq0xivwlkriz.png)
The time taken is
![t = 0.455 \ s](https://img.qammunity.org/2021/formulas/physics/college/e61xchuqzd0io15drbq7lr1x9qlagl3t3k.png)
The horizontal component of the speed of the dart is mathematically represented as
![u_x = ucos \theta](https://img.qammunity.org/2021/formulas/physics/college/zktwslpzk66p8r0utme0mkqoi6fvtyifjp.png)
where u is the the velocity at dart is lunched
so
![distance = velocity \ in \ the\ x-direction * time](https://img.qammunity.org/2021/formulas/physics/college/zsgh9eu82aucx9418dykf442oazz9f6ge0.png)
substituting values
![3.66 = ucos \theta * (0.455)](https://img.qammunity.org/2021/formulas/physics/college/rmhl51ix3yhpcm8hl405b5u7zdrqdqdefr.png)
=>
![ucos \theta = 8.04 \ m/s](https://img.qammunity.org/2021/formulas/physics/college/yjt11j7cssaie2sxtxlsufhqqvm85jt5rz.png)
From projectile kinematics the time taken by the dart can be mathematically represented as
![t = (2usin \theta )/(g)](https://img.qammunity.org/2021/formulas/physics/college/r2fmnbrglgmoja7grqwoalupbao51hjme6.png)
=>
![usin \theta = (g * t)/(2 )](https://img.qammunity.org/2021/formulas/physics/college/wc8qd3x1l6iy4n6vk5gkwku7uqr3j3enxj.png)
![usin \theta = (9.8 * 0.455)/(2 )](https://img.qammunity.org/2021/formulas/physics/college/ofqdvjsc48s9jesp98q5iua4kpkr46bm08.png)
![usin \theta = 2.23](https://img.qammunity.org/2021/formulas/physics/college/xhz3jbcu6x4urv26bgk1j2mp245h7p61ay.png)
=>
![tan \theta = (usin\theta )/(ucos \theta ) = (2.23)/(8.04)](https://img.qammunity.org/2021/formulas/physics/college/ph1037m0jv3sk2n306xltvxbor2hxo3okf.png)
![\theta = tan^(-1) [0.277]](https://img.qammunity.org/2021/formulas/physics/college/8ir28ozjkanhurrjkwqjskbenb95mywayh.png)
![\theta = 15.48^o](https://img.qammunity.org/2021/formulas/physics/college/kz2dzm6hjwpw3u2vub80i6r1038cspbgtc.png)