The Kingdom of Mathematics and Famous Detectives

"I..."

Furuhashi said in a lonely voice, "I lost interest in snacks..."

"Eh, Onee-san doesn't like eating snacks today?!"

Rin made a leaning motion, widened her eyes, and had an extraordinary expression on her face.

Since Naoki and Nanjo are both members of the library committee, Rin often runs around to play when she is free, and knows that Furuhashi likes snacks.

You could say 'no longer like snacks' now like cats suddenly don't like fish and pandas don't like bamboo, which makes people's views fall.

"Is Onee-san okay?" Rin approached and asked worriedly, "Are you sick? Or does that mean the end of the world will come tomorrow?"

"It's just that I don't eat snacks, the end of the world hasn't come yet!" Furuhashi complained.

"Thats..."

Furuhashi said hesitantly, "I caught a cold, and I couldn't taste the food today… that's all."

"I see, it scares me."

Rin raised her hand and patted her poor chest, then said, "Didn't Onee-san say that there is only one person in the family, because you are sick, you will go home with Nii-chan at night and ask my mother to give it to you..."

"Cough, cough, cough!"

Seeing Yuika tilting her head and looking curiously, Furuhashi hastily interrupted with a cough, and her face quickly turned red: "It's just a common cold, I will go home and take cold medicine at night!"

There are still outsiders, the meeting with the parents at Asakawa-san's house must be kept secret, and don't say a word!

"Asakawa-san, how did you resolve this matter?" In order to avoid Rin's endless entanglement, Furuhashi hastily moved his butt and approached Naoki, holding an exercise book in his hand, and quickly said, "Trigonometry problems"

In textbooks it is clearly written that trigonometric functions are one of the basic functions included in basic knowledge that [can be mastered and must be mastered].

Naoki twirled the pencil on his fingertip, pondered for a while, and finally thought of a teaching method that Furuhashi could possibly understand.

"Good morning, a murder case suddenly occurred in the Royal City of Mathematics..."

"Eh? Homicides?"

Furuhashi was surprised, and she straightened his waist and looked nervous.

"The police couldn't do anything about this murder, so they invited a famous detective, Furuhashi who was wearing a black raincoat, high hat, biting a pipe, and saluting to help solve the case."

"What." Furuhashi raised his hand to cover his cheek, his voice embarrassed, "A famous detective, I can only be considered a third-rate detective at most."

How nice of you to say that! You can't even learn basic trigonometric functions. Once you find a math puzzle in the process of solving a case, you'll be knocked out in an instant! Not to mention a third-rate detective, your current level isn't even an assistant detective. Watson can still find clues to Sherlock Holmes. Other than your empty eyes, you only play the role of a snack destroyer!

Naoki continued: "Famous detective Furuhashi bit his pipe and walked to the house of the murdered man."

"I don't know how to bite a pipe." Furuhashi whispered, "Smoking is harmful to health, and the smell of smoke is the most annoying thing, so don't smoke in the future..."

"What?"

"It doesn't matter." Furuhashi covered her pink lips with her right hand, her eyes wandering, "Continue Asakawa-san."

"Walking into the house, the famous detective Furuhashi immediately made his first discovery. The dome of the victim's room is actually round."

Naoki took a scratching paper and randomly drew a semi-circle on it.

"The dome?" Furuhashi asked curiously, "Could it be a Hobbit?"

The graphs and curves of all trigonometric functions are very smooth, and the fat dwarves fit the picture better than the skinny hobbits!

"Don't talk, just keep listening." Naoki's expression was serious, "You are a famous detective now, with the mission of finding the killer and correcting the injustice of the victim, don't jump to conclusions, it will allow the real killer to go unpunished."

"Understood."

Furuhashi opened his eyes wide and continued to listen to Naoki's story about the case.

"Besides the dome, there is a hanging film screen in the room..."

Naoki drew a line perpendicular to the ground on an ellipse with a pen, "This is a movie screen."

Then draw a dot in the middle of the line at the bottom, "You stand in the middle of the room and look at the very top of the movie screen. This line is your line of sight."

Naoki connected the dots and lines on the paper, quickly drew a triangle, and turned to look at Furuhashi, "The so-called sine function is the ratio of the distance between this film screen and you."

"The farther you are from the movie screen, the smaller the screen, and the bigger the screen, the closer you are." Naoki wrote down the basic formula for the sine function, turned to look at Furuhashi, and asked, "What do you think about this work? When will the screen be the biggest?"

"That,…" Furuhashi stretched out a finger at the paper, and said doubtfully, "When it was hanging in the middle of the roof?"

"Very good, you are right." Naoki nodded lightly, "Congratulations to the famous detective Furuhashi for finding the first clue."

"This is all thanks to Asakawa-san, it has nothing to do with me."

Saying this, the corners of Furuhashi's pink lips clearly outlined a happy arc upwards.

In a sense, women, like pets, need to be cherished from time to time, and Naoki is undoubtedly the same.

Naoki continued: "When the movie screen is at its largest, what is your line of sight?"

"It's 90 degrees."

Furuhashi quickly said: "A matter like this is still hard for me to say."

"The answer is correct, congratulations to detective Furuhashi for finding the second clue, which is the maximum value of the sine function."

Naoki drew the coordinate axes of the plane with Furuhashi as the center, "After careful observation, the famous detective Furuhashi discovered that there are identical semicircular buildings and film screens underground, therefore upside down. See so negative angle..."

Naoki drew a standard graph of the sine function on paper, and kept asking, "How many degrees should this be?"

"that..."

Furuhashi hesitated and whispered, "Is it 90 degrees?"

"When is zero?"

"180 degrees."

"Good, all answers are correct." Naoki marked the degrees corresponding to the maximum and minimum values of the function curves in the figure, and finally concluded, "The sine function is the screen size of the home film."

"In the same way, the cosine function is how far the movie screen is from you..."

"I understand."

Furuhashi tilted his head and looked at Naoki, his face full of curiosity: "But Asakawa-san hasn't said why the victim was killed yet?"